/*-------------------------------------------------------------------------
 *
 * pl_exec.c		- Executor for the PL/pgSQL
 *			  procedural language
 *
 * Portions Copyright (c) 1996-2009, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *	  $PostgreSQL: pgsql/src/pl/plpgsql/src/pl_exec.c,v 1.180.2.5 2007/04/19 16:33:32 tgl Exp $
 *
 *-------------------------------------------------------------------------
 */

#include "plpgsql.h"
#include "pl_gram.h"

#include <ctype.h>

#include "access/heapam.h"
#include "access/transam.h"
#include "catalog/pg_proc.h"
#include "catalog/pg_type.h"
#include "cdb/cdbvars.h"
#include "executor/spi_priv.h"
#include "funcapi.h"
#include "optimizer/clauses.h"
#include "parser/parse_expr.h"
#include "parser/scansup.h"
#include "tcop/tcopprot.h"
#include "utils/array.h"
#include "utils/builtins.h"
#include "utils/lsyscache.h"
#include "utils/memutils.h"
#include "utils/typcache.h"


static const char *const raise_skip_msg = "RAISE";

/*
 * All plpgsql function executions within a single transaction share the same
 * executor EState for evaluating "simple" expressions.  Each function call
 * creates its own "eval_econtext" ExprContext within this estate for
 * per-evaluation workspace.  eval_econtext is freed at normal function exit,
 * and the EState is freed at transaction end (in case of error, we assume
 * that the abort mechanisms clean it all up).  In order to be sure
 * ExprContext callbacks are handled properly, each subtransaction has to have
 * its own such EState; hence we need a stack.  We use a simple counter to
 * distinguish different instantiations of the EState, so that we can tell
 * whether we have a current copy of a prepared expression.
 *
 * This arrangement is a bit tedious to maintain, but it's worth the trouble
 * so that we don't have to re-prepare simple expressions on each trip through
 * a function.  (We assume the case to optimize is many repetitions of a
 * function within a transaction.)
 */
typedef struct SimpleEstateStackEntry
{
	EState *xact_eval_estate;				/* EState for current xact level */
	long int	xact_estate_simple_id;		/* ID for xact_eval_estate */
	SubTransactionId xact_subxid;			/* ID for current subxact */
	struct SimpleEstateStackEntry *next;	/* next stack entry up */
} SimpleEstateStackEntry;

static SimpleEstateStackEntry *simple_estate_stack = NULL;
static long int simple_estate_id_counter = 0;

/************************************************************
 * Local function forward declarations
 ************************************************************/
static void plpgsql_exec_error_callback(void *arg);
static PLpgSQL_datum *copy_plpgsql_datum(PLpgSQL_datum *datum);

static int exec_stmt_block(PLpgSQL_execstate *estate,
				PLpgSQL_stmt_block *block);
static int exec_stmts(PLpgSQL_execstate *estate,
		   List *stmts);
static int exec_stmt(PLpgSQL_execstate *estate,
		  PLpgSQL_stmt *stmt);
static int exec_stmt_assign(PLpgSQL_execstate *estate,
				 PLpgSQL_stmt_assign *stmt);
static int exec_stmt_perform(PLpgSQL_execstate *estate,
				  PLpgSQL_stmt_perform *stmt);
static int exec_stmt_getdiag(PLpgSQL_execstate *estate,
				  PLpgSQL_stmt_getdiag *stmt);
static int exec_stmt_if(PLpgSQL_execstate *estate,
			 PLpgSQL_stmt_if *stmt);
static int exec_stmt_loop(PLpgSQL_execstate *estate,
			   PLpgSQL_stmt_loop *stmt);
static int exec_stmt_while(PLpgSQL_execstate *estate,
				PLpgSQL_stmt_while *stmt);
static int exec_stmt_fori(PLpgSQL_execstate *estate,
			   PLpgSQL_stmt_fori *stmt);
static int exec_stmt_fors(PLpgSQL_execstate *estate,
			   PLpgSQL_stmt_fors *stmt);
static int exec_stmt_open(PLpgSQL_execstate *estate,
			   PLpgSQL_stmt_open *stmt);
static int exec_stmt_fetch(PLpgSQL_execstate *estate,
				PLpgSQL_stmt_fetch *stmt);
static int exec_stmt_close(PLpgSQL_execstate *estate,
				PLpgSQL_stmt_close *stmt);
static int exec_stmt_exit(PLpgSQL_execstate *estate,
			   PLpgSQL_stmt_exit *stmt);
static int exec_stmt_return(PLpgSQL_execstate *estate,
				 PLpgSQL_stmt_return *stmt);
static int exec_stmt_return_next(PLpgSQL_execstate *estate,
					  PLpgSQL_stmt_return_next *stmt);
static int exec_stmt_raise(PLpgSQL_execstate *estate,
				PLpgSQL_stmt_raise *stmt);
static int exec_stmt_execsql(PLpgSQL_execstate *estate,
				  PLpgSQL_stmt_execsql *stmt);
static int exec_stmt_dynexecute(PLpgSQL_execstate *estate,
					 PLpgSQL_stmt_dynexecute *stmt);
static int exec_stmt_dynfors(PLpgSQL_execstate *estate,
				  PLpgSQL_stmt_dynfors *stmt);

static void plpgsql_estate_setup(PLpgSQL_execstate *estate,
					 PLpgSQL_function *func,
					 ReturnSetInfo *rsi);
static void exec_eval_cleanup(PLpgSQL_execstate *estate);

static void exec_prepare_plan(PLpgSQL_execstate *estate,
				  PLpgSQL_expr *expr);
static bool exec_simple_check_node(Node *node);
static void exec_simple_check_plan(PLpgSQL_expr *expr);
static Datum exec_eval_simple_expr(PLpgSQL_execstate *estate,
					  PLpgSQL_expr *expr,
					  bool *isNull,
					  Oid *rettype);

static void exec_assign_expr(PLpgSQL_execstate *estate,
				 PLpgSQL_datum *target,
				 PLpgSQL_expr *expr);
static void exec_assign_value(PLpgSQL_execstate *estate,
				  PLpgSQL_datum *target,
				  Datum value, Oid valtype, bool *isNull);
static void exec_eval_datum(PLpgSQL_execstate *estate,
				PLpgSQL_datum *datum,
				Oid expectedtypeid,
				Oid *typeid,
				Datum *value,
				bool *isnull);
static int exec_eval_integer(PLpgSQL_execstate *estate,
				  PLpgSQL_expr *expr,
				  bool *isNull);
static bool exec_eval_boolean(PLpgSQL_execstate *estate,
				  PLpgSQL_expr *expr,
				  bool *isNull);
static Datum exec_eval_expr(PLpgSQL_execstate *estate,
			   PLpgSQL_expr *expr,
			   bool *isNull,
			   Oid *rettype);
static int exec_run_select(PLpgSQL_execstate *estate,
				PLpgSQL_expr *expr, long maxtuples, Portal *portalP);
static void exec_move_row(PLpgSQL_execstate *estate,
			  PLpgSQL_rec *rec,
			  PLpgSQL_row *row,
			  HeapTuple tup, TupleDesc tupdesc);
static HeapTuple make_tuple_from_row(PLpgSQL_execstate *estate,
					PLpgSQL_row *row,
					TupleDesc tupdesc);
static char *convert_value_to_string(Datum value, Oid valtype);
static Datum exec_cast_value(Datum value, Oid valtype,
				Oid reqtype,
				FmgrInfo *reqinput,
				Oid reqtypioparam,
				int32 reqtypmod,
				bool isnull);
static Datum exec_simple_cast_value(Datum value, Oid valtype,
					   Oid reqtype, int32 reqtypmod,
					   bool isnull);
static void exec_init_tuple_store(PLpgSQL_execstate *estate);
static bool compatible_tupdesc(TupleDesc td1, TupleDesc td2);
static void exec_set_found(PLpgSQL_execstate *estate, bool state);
static void plpgsql_create_econtext(PLpgSQL_execstate *estate);
static void free_var(PLpgSQL_var *var);
static void exec_check_cache_plan(PLpgSQL_expr *expr);
static void exec_free_plan(PLpgSQL_expr *expr);


/* ----------
 * plpgsql_exec_function	Called by the call handler for
 *				function execution.
 * ----------
 */
Datum
plpgsql_exec_function(PLpgSQL_function *func, FunctionCallInfo fcinfo)
{
	PLpgSQL_execstate estate;
	ErrorContextCallback plerrcontext;
	int			i;
	int			rc;

	/*
	 * Setup the execution state
	 */
	plpgsql_estate_setup(&estate, func, (ReturnSetInfo *) fcinfo->resultinfo);

	/*
	 * Setup error traceback support for ereport()
	 */
	plerrcontext.callback = plpgsql_exec_error_callback;
	plerrcontext.arg = &estate;
	plerrcontext.previous = error_context_stack;
	error_context_stack = &plerrcontext;

	/*
	 * Make local execution copies of all the datums
	 */
	estate.err_text = gettext_noop("during initialization of execution state");
	for (i = 0; i < estate.ndatums; i++)
		estate.datums[i] = copy_plpgsql_datum(func->datums[i]);

	/*
	 * Store the actual call argument values into the appropriate variables
	 */
	estate.err_text = gettext_noop("while storing call arguments into local variables");
	for (i = 0; i < func->fn_nargs; i++)
	{
		int			n = func->fn_argvarnos[i];

		switch (estate.datums[n]->dtype)
		{
			case PLPGSQL_DTYPE_VAR:
				{
					PLpgSQL_var *var = (PLpgSQL_var *) estate.datums[n];

					var->value = fcinfo->arg[i];
					var->isnull = fcinfo->argnull[i];
					var->freeval = false;
				}
				break;

			case PLPGSQL_DTYPE_ROW:
				{
					PLpgSQL_row *row = (PLpgSQL_row *) estate.datums[n];

					if (!fcinfo->argnull[i])
					{
						HeapTupleHeader td;
						Oid			tupType;
						int32		tupTypmod;
						TupleDesc	tupdesc;
						HeapTupleData tmptup;

						td = DatumGetHeapTupleHeader(fcinfo->arg[i]);
						/* Extract rowtype info and find a tupdesc */
						tupType = HeapTupleHeaderGetTypeId(td);
						tupTypmod = HeapTupleHeaderGetTypMod(td);
						tupdesc = lookup_rowtype_tupdesc(tupType, tupTypmod);
						/* Build a temporary HeapTuple control structure */
						tmptup.t_len = HeapTupleHeaderGetDatumLength(td);
						ItemPointerSetInvalid(&(tmptup.t_self));
						//tmptup.t_tableOid = InvalidOid;
						tmptup.t_data = td;
						exec_move_row(&estate, NULL, row, &tmptup, tupdesc);
						ReleaseTupleDesc(tupdesc);
					}
					else
					{
						/* If arg is null, treat it as an empty row */
						exec_move_row(&estate, NULL, row, NULL, NULL);
					}
				}
				break;

			default:
				elog(ERROR, "unrecognized dtype: %d", func->datums[i]->dtype);
		}
	}

	estate.err_text = gettext_noop("during function entry");

	/*
	 * Set the magic variable FOUND to false
	 */
	exec_set_found(&estate, false);

	/*
	 * Let the instrumentation plugin peek at this function
	 */
	if (*plugin_ptr && (*plugin_ptr)->func_beg)
		((*plugin_ptr)->func_beg) (&estate, func);

	/*
	 * Now call the toplevel block of statements
	 */
	estate.err_text = NULL;
	estate.err_stmt = (PLpgSQL_stmt *) (func->action);
	rc = exec_stmt_block(&estate, func->action);
	if (rc != PLPGSQL_RC_RETURN)
	{
		estate.err_stmt = NULL;
		estate.err_text = NULL;

		/*
		 * Provide a more helpful message if a CONTINUE or RAISE has been used
		 * outside the context it can work in.
		 */
		if (rc == PLPGSQL_RC_CONTINUE)
			ereport(ERROR,
					(errcode(ERRCODE_SYNTAX_ERROR),
					 errmsg("CONTINUE cannot be used outside a loop")));
		else
			ereport(ERROR,
			   (errcode(ERRCODE_S_R_E_FUNCTION_EXECUTED_NO_RETURN_STATEMENT),
				errmsg("control reached end of function without RETURN")));
	}

	/*
	 * We got a return value - process it
	 */
	estate.err_stmt = NULL;
	estate.err_text = gettext_noop("while casting return value to function's return type");

	fcinfo->isnull = estate.retisnull;

	if (estate.retisset)
	{
		ReturnSetInfo *rsi = estate.rsi;

		/* Check caller can handle a set result */
		if (!rsi || !IsA(rsi, ReturnSetInfo) ||
			(rsi->allowedModes & SFRM_Materialize) == 0)
			ereport(ERROR,
					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
					 errmsg("set-valued function called in context that cannot accept a set")));
		rsi->returnMode = SFRM_Materialize;

		/* If we produced any tuples, send back the result */
		if (estate.tuple_store)
		{
			rsi->setResult = estate.tuple_store;
			if (estate.rettupdesc)
			{
				MemoryContext oldcxt;

				oldcxt = MemoryContextSwitchTo(estate.tuple_store_cxt);
				rsi->setDesc = CreateTupleDescCopy(estate.rettupdesc);
				MemoryContextSwitchTo(oldcxt);
			}
		}
		estate.retval = (Datum) 0;
		fcinfo->isnull = true;
	}
	else if (!estate.retisnull)
	{
		if (estate.retistuple)
		{
			/*
			 * We have to check that the returned tuple actually matches the
			 * expected result type.  XXX would be better to cache the tupdesc
			 * instead of repeating get_call_result_type()
			 */
			TupleDesc	tupdesc;

			switch (get_call_result_type(fcinfo, NULL, &tupdesc))
			{
				case TYPEFUNC_COMPOSITE:
					/* got the expected result rowtype, now check it */
					if (estate.rettupdesc == NULL ||
						!compatible_tupdesc(estate.rettupdesc, tupdesc))
						ereport(ERROR,
								(errcode(ERRCODE_DATATYPE_MISMATCH),
								 errmsg("returned record type does not match expected record type")));
					break;
				case TYPEFUNC_RECORD:

					/*
					 * Failed to determine actual type of RECORD.  We could
					 * raise an error here, but what this means in practice is
					 * that the caller is expecting any old generic rowtype,
					 * so we don't really need to be restrictive. Pass back
					 * the generated result type, instead.
					 */
					tupdesc = estate.rettupdesc;
					if (tupdesc == NULL)		/* shouldn't happen */
						elog(ERROR, "return type must be a row type");
					break;
				default:
					/* shouldn't get here if retistuple is true ... */
					elog(ERROR, "return type must be a row type");
					break;
			}

			/*
			 * Copy tuple to upper executor memory, as a tuple Datum. Make
			 * sure it is labeled with the caller-supplied tuple type.
			 */
			estate.retval =
				PointerGetDatum(SPI_returntuple((HeapTuple) DatumGetPointer(estate.retval),
												tupdesc));
		}
		else
		{
			/* Cast value to proper type */
			estate.retval = exec_cast_value(estate.retval, estate.rettype,
											func->fn_rettype,
											&(func->fn_retinput),
											func->fn_rettypioparam,
											-1,
											fcinfo->isnull);

			/*
			 * If the function's return type isn't by value, copy the value
			 * into upper executor memory context.
			 */
			if (!fcinfo->isnull && !func->fn_retbyval)
			{
				Size		len;
				void	   *tmp;

				len = datumGetSize(estate.retval, false, func->fn_rettyplen);
				tmp = SPI_palloc(len);
				memcpy(tmp, DatumGetPointer(estate.retval), len);
				estate.retval = PointerGetDatum(tmp);
			}
		}
	}

	estate.err_text = gettext_noop("during function exit");

	/*
	 * Let the instrumentation plugin peek at this function
	 */
	if (*plugin_ptr && (*plugin_ptr)->func_end)
		((*plugin_ptr)->func_end) (&estate, func);

	/* Clean up any leftover temporary memory */
	FreeExprContext(estate.eval_econtext);
	estate.eval_econtext = NULL;
	exec_eval_cleanup(&estate);

	/*
	 * Pop the error context stack
	 */
	error_context_stack = plerrcontext.previous;

	/*
	 * Return the function's result
	 */
	return estate.retval;
}


/* ----------
 * plpgsql_exec_trigger		Called by the call handler for
 *				trigger execution.
 * ----------
 */
HeapTuple
plpgsql_exec_trigger(PLpgSQL_function *func,
					 TriggerData *trigdata)
{
	PLpgSQL_execstate estate;
	ErrorContextCallback plerrcontext;
	int			i;
	int			rc;
	PLpgSQL_var *var;
	PLpgSQL_rec *rec_new,
			   *rec_old;
	HeapTuple	rettup;

	/*
	 * Setup the execution state
	 */
	plpgsql_estate_setup(&estate, func, NULL);

	/*
	 * Setup error traceback support for ereport()
	 */
	plerrcontext.callback = plpgsql_exec_error_callback;
	plerrcontext.arg = &estate;
	plerrcontext.previous = error_context_stack;
	error_context_stack = &plerrcontext;

	/*
	 * Make local execution copies of all the datums
	 */
	estate.err_text = gettext_noop("during initialization of execution state");
	for (i = 0; i < estate.ndatums; i++)
		estate.datums[i] = copy_plpgsql_datum(func->datums[i]);

	/*
	 * Put the OLD and NEW tuples into record variables
	 */
	rec_new = (PLpgSQL_rec *) (estate.datums[func->new_varno]);
	rec_new->freetup = false;
	rec_new->freetupdesc = false;
	rec_old = (PLpgSQL_rec *) (estate.datums[func->old_varno]);
	rec_old->freetup = false;
	rec_old->freetupdesc = false;

	if (TRIGGER_FIRED_FOR_STATEMENT(trigdata->tg_event))
	{
		/*
		 * Per-statement triggers don't use OLD/NEW variables
		 */
		rec_new->tup = NULL;
		rec_new->tupdesc = NULL;
		rec_old->tup = NULL;
		rec_old->tupdesc = NULL;
	}
	else if (TRIGGER_FIRED_BY_INSERT(trigdata->tg_event))
	{
		rec_new->tup = trigdata->tg_trigtuple;
		rec_new->tupdesc = trigdata->tg_relation->rd_att;
		rec_old->tup = NULL;
		rec_old->tupdesc = NULL;
	}
	else if (TRIGGER_FIRED_BY_UPDATE(trigdata->tg_event))
	{
		rec_new->tup = trigdata->tg_newtuple;
		rec_new->tupdesc = trigdata->tg_relation->rd_att;
		rec_old->tup = trigdata->tg_trigtuple;
		rec_old->tupdesc = trigdata->tg_relation->rd_att;
	}
	else if (TRIGGER_FIRED_BY_DELETE(trigdata->tg_event))
	{
		rec_new->tup = NULL;
		rec_new->tupdesc = NULL;
		rec_old->tup = trigdata->tg_trigtuple;
		rec_old->tupdesc = trigdata->tg_relation->rd_att;
	}
	else
		elog(ERROR, "unrecognized trigger action: not INSERT, DELETE, or UPDATE");

	/*
	 * Assign the special tg_ variables
	 */

	var = (PLpgSQL_var *) (estate.datums[func->tg_op_varno]);
	if (TRIGGER_FIRED_BY_INSERT(trigdata->tg_event))
		var->value = DirectFunctionCall1(textin, CStringGetDatum("INSERT"));
	else if (TRIGGER_FIRED_BY_UPDATE(trigdata->tg_event))
		var->value = DirectFunctionCall1(textin, CStringGetDatum("UPDATE"));
	else if (TRIGGER_FIRED_BY_DELETE(trigdata->tg_event))
		var->value = DirectFunctionCall1(textin, CStringGetDatum("DELETE"));
	else
		elog(ERROR, "unrecognized trigger action: not INSERT, DELETE, or UPDATE");
	var->isnull = false;
	var->freeval = true;

	var = (PLpgSQL_var *) (estate.datums[func->tg_name_varno]);
	var->value = DirectFunctionCall1(namein,
							  CStringGetDatum(trigdata->tg_trigger->tgname));
	var->isnull = false;
	var->freeval = true;

	var = (PLpgSQL_var *) (estate.datums[func->tg_when_varno]);
	if (TRIGGER_FIRED_BEFORE(trigdata->tg_event))
		var->value = DirectFunctionCall1(textin, CStringGetDatum("BEFORE"));
	else if (TRIGGER_FIRED_AFTER(trigdata->tg_event))
		var->value = DirectFunctionCall1(textin, CStringGetDatum("AFTER"));
	else
		elog(ERROR, "unrecognized trigger execution time: not BEFORE or AFTER");
	var->isnull = false;
	var->freeval = true;

	var = (PLpgSQL_var *) (estate.datums[func->tg_level_varno]);
	if (TRIGGER_FIRED_FOR_ROW(trigdata->tg_event))
		var->value = DirectFunctionCall1(textin, CStringGetDatum("ROW"));
	else if (TRIGGER_FIRED_FOR_STATEMENT(trigdata->tg_event))
		var->value = DirectFunctionCall1(textin, CStringGetDatum("STATEMENT"));
	else
		elog(ERROR, "unrecognized trigger event type: not ROW or STATEMENT");
	var->isnull = false;
	var->freeval = true;

	var = (PLpgSQL_var *) (estate.datums[func->tg_relid_varno]);
	var->value = ObjectIdGetDatum(trigdata->tg_relation->rd_id);
	var->isnull = false;
	var->freeval = false;

	var = (PLpgSQL_var *) (estate.datums[func->tg_relname_varno]);
	var->value = DirectFunctionCall1(namein,
			CStringGetDatum(RelationGetRelationName(trigdata->tg_relation)));
	var->isnull = false;
	var->freeval = true;

	var = (PLpgSQL_var *) (estate.datums[func->tg_table_name_varno]);
	var->value = DirectFunctionCall1(namein,
			CStringGetDatum(RelationGetRelationName(trigdata->tg_relation)));
	var->isnull = false;
	var->freeval = true;

	var = (PLpgSQL_var *) (estate.datums[func->tg_table_schema_varno]);
	var->value = DirectFunctionCall1(namein,
									 CStringGetDatum(
													 get_namespace_name(
														RelationGetNamespace(
												   trigdata->tg_relation))));
	var->isnull = false;
	var->freeval = true;

	var = (PLpgSQL_var *) (estate.datums[func->tg_nargs_varno]);
	var->value = Int16GetDatum(trigdata->tg_trigger->tgnargs);
	var->isnull = false;
	var->freeval = false;

	/*
	 * Store the trigger argument values into the special execution state
	 * variables
	 */
	estate.err_text = gettext_noop("while storing call arguments into local variables");
	estate.trig_nargs = trigdata->tg_trigger->tgnargs;
	if (estate.trig_nargs == 0)
		estate.trig_argv = NULL;
	else
	{
		estate.trig_argv = palloc(sizeof(Datum) * estate.trig_nargs);
		for (i = 0; i < trigdata->tg_trigger->tgnargs; i++)
			estate.trig_argv[i] = DirectFunctionCall1(textin,
						   CStringGetDatum(trigdata->tg_trigger->tgargs[i]));
	}

	estate.err_text = gettext_noop("during function entry");

	/*
	 * Set the magic variable FOUND to false
	 */
	exec_set_found(&estate, false);

	/*
	 * Let the instrumentation plugin peek at this function
	 */
	if (*plugin_ptr && (*plugin_ptr)->func_beg)
		((*plugin_ptr)->func_beg) (&estate, func);

	/*
	 * Now call the toplevel block of statements
	 */
	estate.err_text = NULL;
	estate.err_stmt = (PLpgSQL_stmt *) (func->action);
	rc = exec_stmt_block(&estate, func->action);
	if (rc != PLPGSQL_RC_RETURN)
	{
		estate.err_stmt = NULL;
		estate.err_text = NULL;

		/*
		 * Provide a more helpful message if a CONTINUE or RAISE has been used
		 * outside the context it can work in.
		 */
		if (rc == PLPGSQL_RC_CONTINUE)
			ereport(ERROR,
					(errcode(ERRCODE_SYNTAX_ERROR),
					 errmsg("CONTINUE cannot be used outside a loop")));
		else
			ereport(ERROR,
			   (errcode(ERRCODE_S_R_E_FUNCTION_EXECUTED_NO_RETURN_STATEMENT),
				errmsg("control reached end of trigger procedure without RETURN")));
	}

	estate.err_stmt = NULL;
	estate.err_text = gettext_noop("during function exit");

	if (estate.retisset)
		ereport(ERROR,
				(errcode(ERRCODE_DATATYPE_MISMATCH),
				 errmsg("trigger procedure cannot return a set")));

	/*
	 * Check that the returned tuple structure has the same attributes, the
	 * relation that fired the trigger has. A per-statement trigger always
	 * needs to return NULL, so we ignore any return value the function itself
	 * produces (XXX: is this a good idea?)
	 *
	 * XXX This way it is possible, that the trigger returns a tuple where
	 * attributes don't have the correct atttypmod's length. It's up to the
	 * trigger's programmer to ensure that this doesn't happen. Jan
	 */
	if (estate.retisnull || TRIGGER_FIRED_FOR_STATEMENT(trigdata->tg_event))
		rettup = NULL;
	else
	{
		if (!compatible_tupdesc(estate.rettupdesc,
								trigdata->tg_relation->rd_att))
			ereport(ERROR,
					(errcode(ERRCODE_DATATYPE_MISMATCH),
					 errmsg("returned tuple structure does not match table of trigger event")));
		/* Copy tuple to upper executor memory */
		rettup = SPI_copytuple((HeapTuple) DatumGetPointer(estate.retval));
	}

	/*
	 * Let the instrumentation plugin peek at this function
	 */
	if (*plugin_ptr && (*plugin_ptr)->func_end)
		((*plugin_ptr)->func_end) (&estate, func);

	/* Clean up any leftover temporary memory */
	FreeExprContext(estate.eval_econtext);
	estate.eval_econtext = NULL;
	exec_eval_cleanup(&estate);

	/*
	 * Pop the error context stack
	 */
	error_context_stack = plerrcontext.previous;

	/*
	 * Return the trigger's result
	 */
	return rettup;
}


/*
 * error context callback to let us supply a call-stack traceback
 */
static void
plpgsql_exec_error_callback(void *arg)
{
	PLpgSQL_execstate *estate = (PLpgSQL_execstate *) arg;

	/* safety check, shouldn't happen */
	if (estate->err_func == NULL)
		return;

	/* if we are doing RAISE, don't report its location */
	if (estate->err_text == raise_skip_msg)
		return;

	if (estate->err_text != NULL)
	{
		/*
		 * We don't expend the cycles to run gettext() on err_text unless we
		 * actually need it.  Therefore, places that set up err_text should
		 * use gettext_noop() to ensure the strings get recorded in the
		 * message dictionary.
		 *
		 * If both err_text and err_stmt are set, use the err_text as
		 * description, but report the err_stmt's line number.  When err_stmt
		 * is not set, we're in function entry/exit, or some such place not
		 * attached to a specific line number.
		 */
		if (estate->err_stmt != NULL)
		{
			/*
			 * translator: last %s is a phrase such as "during statement block
			 * local variable initialization"
			 */
			errcontext("PL/pgSQL function \"%s\" line %d %s",
					   estate->err_func->fn_name,
					   estate->err_stmt->lineno,
					   _(estate->err_text));
		}
		else
		{
		/*
		 * translator: last %s is a phrase such as "while storing call
		 * arguments into local variables"
		 */
		errcontext("PL/pgSQL function \"%s\" %s",
				   estate->err_func->fn_name,
					   _(estate->err_text));
		}
	}
	else if (estate->err_stmt != NULL)
	{
		/* translator: last %s is a plpgsql statement type name */
		errcontext("PL/pgSQL function \"%s\" line %d at %s",
				   estate->err_func->fn_name,
				   estate->err_stmt->lineno,
				   plpgsql_stmt_typename(estate->err_stmt));
	}
	else
		errcontext("PL/pgSQL function \"%s\"",
				   estate->err_func->fn_name);
}


/* ----------
 * Support function for initializing local execution variables
 * ----------
 */
static PLpgSQL_datum *
copy_plpgsql_datum(PLpgSQL_datum *datum)
{
	PLpgSQL_datum *result;

	switch (datum->dtype)
	{
		case PLPGSQL_DTYPE_VAR:
			{
				PLpgSQL_var *new = palloc(sizeof(PLpgSQL_var));

				memcpy(new, datum, sizeof(PLpgSQL_var));
				/* Ensure the value is null (possibly not needed?) */
				new->value = 0;
				new->isnull = true;
				new->freeval = false;

				result = (PLpgSQL_datum *) new;
			}
			break;

		case PLPGSQL_DTYPE_REC:
			{
				PLpgSQL_rec *new = palloc(sizeof(PLpgSQL_rec));

				memcpy(new, datum, sizeof(PLpgSQL_rec));
				/* Ensure the value is null (possibly not needed?) */
				new->tup = NULL;
				new->tupdesc = NULL;
				new->freetup = false;
				new->freetupdesc = false;

				result = (PLpgSQL_datum *) new;
			}
			break;

		case PLPGSQL_DTYPE_ROW:
		case PLPGSQL_DTYPE_RECFIELD:
		case PLPGSQL_DTYPE_ARRAYELEM:
		case PLPGSQL_DTYPE_TRIGARG:

			/*
			 * These datum records are read-only at runtime, so no need to
			 * copy them
			 */
			result = datum;
			break;

		default:
			elog(ERROR, "unrecognized dtype: %d", datum->dtype);
			result = NULL;		/* keep compiler quiet */
			break;
	}

	return result;
}


static bool
exception_matches_conditions(ErrorData *edata, PLpgSQL_condition *cond)
{
	for (; cond != NULL; cond = cond->next)
	{
		int			sqlerrstate = cond->sqlerrstate;

		/*
		 * OTHERS matches everything *except* query-canceled; if you're
		 * foolish enough, you can match that explicitly.
		 */
		if (sqlerrstate == 0)
		{
			if (edata->sqlerrcode != ERRCODE_QUERY_CANCELED)
				return true;
		}
		/* Exact match? */
		else if (edata->sqlerrcode == sqlerrstate)
			return true;
		/* Category match? */
		else if (ERRCODE_IS_CATEGORY(sqlerrstate) &&
				 ERRCODE_TO_CATEGORY(edata->sqlerrcode) == sqlerrstate)
			return true;
	}
	return false;
}


/* ----------
 * exec_stmt_block			Execute a block of statements
 * ----------
 */
static int
exec_stmt_block(PLpgSQL_execstate *estate, PLpgSQL_stmt_block *block)
{
	volatile int rc = -1;
	int			i;
	int			n;

	/*
	 * First initialize all variables declared in this block
	 */
	estate->err_text = gettext_noop("during statement block local variable initialization");

	for (i = 0; i < block->n_initvars; i++)
	{
		n = block->initvarnos[i];

		switch (estate->datums[n]->dtype)
		{
			case PLPGSQL_DTYPE_VAR:
				{
					PLpgSQL_var *var = (PLpgSQL_var *) (estate->datums[n]);

					/* free any old value, in case re-entering block */
					free_var(var);

					/* Initially it contains a NULL */
					var->value = (Datum) 0;
					var->isnull = true;

					if (var->default_val == NULL)
					{
						/*
						 * If needed, give the datatype a chance to reject
						 * NULLs, by assigning a NULL to the variable. We
						 * claim the value is of type UNKNOWN, not the var's
						 * datatype, else coercion will be skipped. (Do this
						 * before the notnull check to be consistent with
						 * exec_assign_value.)
						 */
						if (!var->datatype->typinput.fn_strict)
						{
							bool	valIsNull = true;

							exec_assign_value(estate,
											  (PLpgSQL_datum *) var,
											  (Datum) 0,
											  UNKNOWNOID,
											  &valIsNull);
						}
						if (var->notnull)
							ereport(ERROR,
									(errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
									 errmsg("variable \"%s\" declared NOT NULL cannot default to NULL",
											var->refname)));
					}
					else
					{
						exec_assign_expr(estate, (PLpgSQL_datum *) var,
										 var->default_val);
					}
				}
				break;

			case PLPGSQL_DTYPE_REC:
				{
					PLpgSQL_rec *rec = (PLpgSQL_rec *) (estate->datums[n]);

					if (rec->freetup)
					{
						heap_freetuple(rec->tup);
						FreeTupleDesc(rec->tupdesc);
						rec->freetup = false;
					}

					rec->tup = NULL;
					rec->tupdesc = NULL;
				}
				break;

			case PLPGSQL_DTYPE_RECFIELD:
			case PLPGSQL_DTYPE_ARRAYELEM:
				break;

			default:
				elog(ERROR, "unrecognized dtype: %d",
					 estate->datums[n]->dtype);
		}
	}

	if (block->exceptions)
	{
		/*
		 * Execute the statements in the block's body inside a sub-transaction
		 */
		MemoryContext oldcontext = CurrentMemoryContext;
		ResourceOwner oldowner = CurrentResourceOwner;
		ExprContext *old_eval_econtext = estate->eval_econtext;
		EState	   *old_eval_estate = estate->eval_estate;
		long int	old_eval_estate_simple_id = estate->eval_estate_simple_id;

		estate->err_text = gettext_noop("during statement block entry");

		BeginInternalSubTransaction(NULL);
		/* Want to run statements inside function's memory context */
		MemoryContextSwitchTo(oldcontext);

		PG_TRY();
		{
			/*
			 * We need to run the block's statements with a new eval_econtext
			 * that belongs to the current subtransaction; if we try to use
			 * the outer econtext then ExprContext shutdown callbacks will be
			 * called at the wrong times.
			 */
			plpgsql_create_econtext(estate);

			estate->err_text = NULL;

			/* Run the block's statements */
			rc = exec_stmts(estate, block->body);

			estate->err_text = gettext_noop("during statement block exit");

			/*
			 * If the block ended with RETURN, we may need to copy the return
			 * value out of the subtransaction eval_context.  This is
			 * currently only needed for scalar result types --- rowtype
			 * values will always exist in the function's own memory context.
			 */
			if (rc == PLPGSQL_RC_RETURN &&
				!estate->retisset &&
				!estate->retisnull &&
				estate->rettupdesc == NULL)
			{
				int16		resTypLen;
				bool		resTypByVal;

				get_typlenbyval(estate->rettype, &resTypLen, &resTypByVal);
				estate->retval = datumCopy(estate->retval,
										   resTypByVal, resTypLen);
			}

			/* Commit the inner transaction, return to outer xact context */
			ReleaseCurrentSubTransaction();
			MemoryContextSwitchTo(oldcontext);
			CurrentResourceOwner = oldowner;

			/* Revert to outer eval_econtext */
			estate->eval_econtext = old_eval_econtext;
			estate->eval_estate = old_eval_estate;
			estate->eval_estate_simple_id = old_eval_estate_simple_id;

			/*
			 * AtEOSubXact_SPI() should not have popped any SPI context, but
			 * just in case it did, make sure we remain connected.
			 */
			SPI_restore_connection();
		}
		PG_CATCH();
		{
			ErrorData  *edata;
			ListCell   *e;

			estate->err_text = gettext_noop("during exception cleanup");

			/* Save error info */
			MemoryContextSwitchTo(oldcontext);
			edata = CopyErrorData();
			FlushErrorState();

			/* Abort the inner transaction */
			RollbackAndReleaseCurrentSubTransaction();
			MemoryContextSwitchTo(oldcontext);
			CurrentResourceOwner = oldowner;

			/* Revert to outer eval_econtext */
			estate->eval_econtext = old_eval_econtext;
			estate->eval_estate = old_eval_estate;
			estate->eval_estate_simple_id = old_eval_estate_simple_id;

			/*
			 * If AtEOSubXact_SPI() popped any SPI context of the subxact, it
			 * will have left us in a disconnected state.  We need this hack
			 * to return to connected state.
			 */
			SPI_restore_connection();

			/* Clean up econtext. */
			exec_eval_cleanup(estate);

			/* Look for a matching exception handler */
			foreach(e, block->exceptions->exc_list)
			{
				PLpgSQL_exception *exception = (PLpgSQL_exception *) lfirst(e);

				if (exception_matches_conditions(edata, exception->conditions))
				{
					/*
					 * Initialize the magic SQLSTATE and SQLERRM variables for
					 * the exception block. We needn't do this until we have
					 * found a matching exception.
					 */
					PLpgSQL_var *state_var;
					PLpgSQL_var *errm_var;

					state_var = (PLpgSQL_var *)
						estate->datums[block->exceptions->sqlstate_varno];
					state_var->value = DirectFunctionCall1(textin,
					   CStringGetDatum(unpack_sql_state(edata->sqlerrcode)));
					state_var->freeval = true;
					state_var->isnull = false;

					errm_var = (PLpgSQL_var *)
						estate->datums[block->exceptions->sqlerrm_varno];
					errm_var->value = DirectFunctionCall1(textin,
											CStringGetDatum(edata->message));
					errm_var->freeval = true;
					errm_var->isnull = false;

					rc = exec_stmts(estate, exception->action);

					free_var(state_var);
					state_var->value = (Datum) 0;
					free_var(errm_var);
					errm_var->value = (Datum) 0;
					break;
				}
			}

			/* If no match found, re-throw the error */
			if (e == NULL)
				ReThrowError(edata);
			else
				FreeErrorData(edata);
		}
		PG_END_TRY();
	}
	else
	{
		/*
		 * Just execute the statements in the block's body
		 */
		estate->err_text = NULL;

		rc = exec_stmts(estate, block->body);
	}

	estate->err_text = NULL;

	/*
	 * Handle the return code.
	 */
	switch (rc)
	{
		case PLPGSQL_RC_OK:
		case PLPGSQL_RC_CONTINUE:
		case PLPGSQL_RC_RETURN:
			return rc;

		case PLPGSQL_RC_EXIT:
			if (estate->exitlabel == NULL)
				return PLPGSQL_RC_OK;
			if (block->label == NULL)
				return PLPGSQL_RC_EXIT;
			if (strcmp(block->label, estate->exitlabel))
				return PLPGSQL_RC_EXIT;
			estate->exitlabel = NULL;
			return PLPGSQL_RC_OK;

		default:
			elog(ERROR, "unrecognized rc: %d", rc);
	}

	return PLPGSQL_RC_OK;
}


/* ----------
 * exec_stmts			Iterate over a list of statements
 *				as long as their return code is OK
 * ----------
 */
static int
exec_stmts(PLpgSQL_execstate *estate, List *stmts)
{
	ListCell   *s;

	if (stmts == NIL)
	{
		/*
		 * Ensure we do a CHECK_FOR_INTERRUPTS() even though there is no
		 * statement.  This prevents hangup in a tight loop if, for instance,
		 * there is a LOOP construct with an empty body.
		 */
		CHECK_FOR_INTERRUPTS();
		return PLPGSQL_RC_OK;
	}

	foreach(s, stmts)
	{
		PLpgSQL_stmt *stmt = (PLpgSQL_stmt *) lfirst(s);
		int			rc = exec_stmt(estate, stmt);

		if (rc != PLPGSQL_RC_OK)
			return rc;
	}

	return PLPGSQL_RC_OK;
}


/* ----------
 * exec_stmt			Distribute one statement to the statements
 *				type specific execution function.
 * ----------
 */
static int
exec_stmt(PLpgSQL_execstate *estate, PLpgSQL_stmt *stmt)
{
	PLpgSQL_stmt *save_estmt;
	int			rc = -1;

	save_estmt = estate->err_stmt;
	estate->err_stmt = stmt;

	/* Let the plugin know that we are about to execute this statement */
	if (*plugin_ptr && (*plugin_ptr)->stmt_beg)
		((*plugin_ptr)->stmt_beg) (estate, stmt);

	CHECK_FOR_INTERRUPTS();

	switch (stmt->cmd_type)
	{
		case PLPGSQL_STMT_BLOCK:
			rc = exec_stmt_block(estate, (PLpgSQL_stmt_block *) stmt);
			break;

		case PLPGSQL_STMT_ASSIGN:
			rc = exec_stmt_assign(estate, (PLpgSQL_stmt_assign *) stmt);
			break;

		case PLPGSQL_STMT_PERFORM:
			rc = exec_stmt_perform(estate, (PLpgSQL_stmt_perform *) stmt);
			break;

		case PLPGSQL_STMT_GETDIAG:
			rc = exec_stmt_getdiag(estate, (PLpgSQL_stmt_getdiag *) stmt);
			break;

		case PLPGSQL_STMT_IF:
			rc = exec_stmt_if(estate, (PLpgSQL_stmt_if *) stmt);
			break;

		case PLPGSQL_STMT_LOOP:
			rc = exec_stmt_loop(estate, (PLpgSQL_stmt_loop *) stmt);
			break;

		case PLPGSQL_STMT_WHILE:
			rc = exec_stmt_while(estate, (PLpgSQL_stmt_while *) stmt);
			break;

		case PLPGSQL_STMT_FORI:
			rc = exec_stmt_fori(estate, (PLpgSQL_stmt_fori *) stmt);
			break;

		case PLPGSQL_STMT_FORS:
			rc = exec_stmt_fors(estate, (PLpgSQL_stmt_fors *) stmt);
			break;

		case PLPGSQL_STMT_EXIT:
			rc = exec_stmt_exit(estate, (PLpgSQL_stmt_exit *) stmt);
			break;

		case PLPGSQL_STMT_RETURN:
			rc = exec_stmt_return(estate, (PLpgSQL_stmt_return *) stmt);
			break;

		case PLPGSQL_STMT_RETURN_NEXT:
			rc = exec_stmt_return_next(estate, (PLpgSQL_stmt_return_next *) stmt);
			break;

		case PLPGSQL_STMT_RAISE:
			rc = exec_stmt_raise(estate, (PLpgSQL_stmt_raise *) stmt);
			break;

		case PLPGSQL_STMT_EXECSQL:
			rc = exec_stmt_execsql(estate, (PLpgSQL_stmt_execsql *) stmt);
			break;

		case PLPGSQL_STMT_DYNEXECUTE:
			rc = exec_stmt_dynexecute(estate, (PLpgSQL_stmt_dynexecute *) stmt);
			break;

		case PLPGSQL_STMT_DYNFORS:
			rc = exec_stmt_dynfors(estate, (PLpgSQL_stmt_dynfors *) stmt);
			break;

		case PLPGSQL_STMT_OPEN:
			rc = exec_stmt_open(estate, (PLpgSQL_stmt_open *) stmt);
			break;

		case PLPGSQL_STMT_FETCH:
			rc = exec_stmt_fetch(estate, (PLpgSQL_stmt_fetch *) stmt);
			break;

		case PLPGSQL_STMT_CLOSE:
			rc = exec_stmt_close(estate, (PLpgSQL_stmt_close *) stmt);
			break;

		default:
			estate->err_stmt = save_estmt;
			elog(ERROR, "unrecognized cmdtype: %d", stmt->cmd_type);
	}

	/* Let the plugin know that we have finished executing this statement */
	if (*plugin_ptr && (*plugin_ptr)->stmt_end)
		((*plugin_ptr)->stmt_end) (estate, stmt);

	estate->err_stmt = save_estmt;

	return rc;
}


/* ----------
 * exec_stmt_assign			Evaluate an expression and
 *					put the result into a variable.
 * ----------
 */
static int
exec_stmt_assign(PLpgSQL_execstate *estate, PLpgSQL_stmt_assign *stmt)
{
	Assert(stmt->varno >= 0);

	exec_assign_expr(estate, estate->datums[stmt->varno], stmt->expr);

	return PLPGSQL_RC_OK;
}

/* ----------
 * exec_stmt_perform		Evaluate query and discard result (but set
 *							FOUND depending on whether at least one row
 *							was returned).
 * ----------
 */
static int
exec_stmt_perform(PLpgSQL_execstate *estate, PLpgSQL_stmt_perform *stmt)
{
	PLpgSQL_expr *expr = stmt->expr;

	(void) exec_run_select(estate, expr, 0, NULL);
	exec_set_found(estate, (estate->eval_processed != 0));
	exec_eval_cleanup(estate);

	return PLPGSQL_RC_OK;
}

/* ----------
 * exec_stmt_getdiag					Put internal PG information into
 *										specified variables.
 * ----------
 */
static int
exec_stmt_getdiag(PLpgSQL_execstate *estate, PLpgSQL_stmt_getdiag *stmt)
{
	ListCell   *lc;

	foreach(lc, stmt->diag_items)
	{
		PLpgSQL_diag_item *diag_item = (PLpgSQL_diag_item *) lfirst(lc);
		PLpgSQL_datum *var;
		bool		isnull = false;

		if (diag_item->target <= 0)
			continue;

		var = estate->datums[diag_item->target];

		if (var == NULL)
			continue;

		switch (diag_item->kind)
		{
			case PLPGSQL_GETDIAG_ROW_COUNT:

				exec_assign_value(estate, var,
								  UInt64GetDatum(estate->eval_processed),
								  INT8OID, &isnull);
				break;

			case PLPGSQL_GETDIAG_RESULT_OID:

				exec_assign_value(estate, var,
								  ObjectIdGetDatum(estate->eval_lastoid),
								  OIDOID, &isnull);
				break;

			default:
				elog(ERROR, "unrecognized attribute request: %d",
					 diag_item->kind);
		}
	}

	return PLPGSQL_RC_OK;
}

/* ----------
 * exec_stmt_if				Evaluate a bool expression and
 *					execute the true or false body
 *					conditionally.
 * ----------
 */
static int
exec_stmt_if(PLpgSQL_execstate *estate, PLpgSQL_stmt_if *stmt)
{
	bool		value;
	bool		isnull;

	value = exec_eval_boolean(estate, stmt->cond, &isnull);
	exec_eval_cleanup(estate);

	if (!isnull && value)
	{
		if (stmt->true_body != NIL)
			return exec_stmts(estate, stmt->true_body);
	}
	else
	{
		if (stmt->false_body != NIL)
			return exec_stmts(estate, stmt->false_body);
	}

	return PLPGSQL_RC_OK;
}


/* ----------
 * exec_stmt_loop			Loop over statements until
 *					an exit occurs.
 * ----------
 */
static int
exec_stmt_loop(PLpgSQL_execstate *estate, PLpgSQL_stmt_loop *stmt)
{
	for (;;)
	{
		int			rc = exec_stmts(estate, stmt->body);

		switch (rc)
		{
			case PLPGSQL_RC_OK:
				break;

			case PLPGSQL_RC_EXIT:
				if (estate->exitlabel == NULL)
					return PLPGSQL_RC_OK;
				if (stmt->label == NULL)
					return PLPGSQL_RC_EXIT;
				if (strcmp(stmt->label, estate->exitlabel) != 0)
					return PLPGSQL_RC_EXIT;
				estate->exitlabel = NULL;
				return PLPGSQL_RC_OK;

			case PLPGSQL_RC_CONTINUE:
				if (estate->exitlabel == NULL)
					/* anonymous continue, so re-run the loop */
					break;
				else if (stmt->label != NULL &&
						 strcmp(stmt->label, estate->exitlabel) == 0)
					/* label matches named continue, so re-run loop */
					estate->exitlabel = NULL;
				else
					/* label doesn't match named continue, so propagate upward */
					return PLPGSQL_RC_CONTINUE;
				break;

			case PLPGSQL_RC_RETURN:
				return PLPGSQL_RC_RETURN;

			default:
				elog(ERROR, "unrecognized rc: %d", rc);
		}
	}

	return PLPGSQL_RC_OK;
}


/* ----------
 * exec_stmt_while			Loop over statements as long
 *					as an expression evaluates to
 *					true or an exit occurs.
 * ----------
 */
static int
exec_stmt_while(PLpgSQL_execstate *estate, PLpgSQL_stmt_while *stmt)
{
	for (;;)
	{
		int			rc;
		bool		value;
		bool		isnull;

		value = exec_eval_boolean(estate, stmt->cond, &isnull);
		exec_eval_cleanup(estate);

		if (isnull || !value)
			break;

		rc = exec_stmts(estate, stmt->body);

		switch (rc)
		{
			case PLPGSQL_RC_OK:
				break;

			case PLPGSQL_RC_EXIT:
				if (estate->exitlabel == NULL)
					return PLPGSQL_RC_OK;
				if (stmt->label == NULL)
					return PLPGSQL_RC_EXIT;
				if (strcmp(stmt->label, estate->exitlabel))
					return PLPGSQL_RC_EXIT;
				estate->exitlabel = NULL;
				return PLPGSQL_RC_OK;

			case PLPGSQL_RC_CONTINUE:
				if (estate->exitlabel == NULL)
					/* anonymous continue, so re-run loop */
					break;
				else if (stmt->label != NULL &&
						 strcmp(stmt->label, estate->exitlabel) == 0)
					/* label matches named continue, so re-run loop */
					estate->exitlabel = NULL;
				else
					/* label doesn't match named continue, propagate upward */
					return PLPGSQL_RC_CONTINUE;
				break;

			case PLPGSQL_RC_RETURN:
				return PLPGSQL_RC_RETURN;

			default:
				elog(ERROR, "unrecognized rc: %d", rc);
		}
	}

	return PLPGSQL_RC_OK;
}


/* ----------
 * exec_stmt_fori			Iterate an integer variable
 *					from a lower to an upper value
 *					incrementing or decrementing in BY value
 *					Loop can be left with exit.
 * ----------
 */
static int
exec_stmt_fori(PLpgSQL_execstate *estate, PLpgSQL_stmt_fori *stmt)
{
	PLpgSQL_var *var;
	Datum		value;
	Datum		by_value;
	Oid			valtype;
	bool		isnull;
	bool		found = false;
	int			rc = PLPGSQL_RC_OK;

	var = (PLpgSQL_var *) (estate->datums[stmt->var->varno]);

	/*
	 * Get the value of the lower bound into the loop var
	 */
	value = exec_eval_expr(estate, stmt->lower, &isnull, &valtype);
	value = exec_cast_value(value, valtype, var->datatype->typoid,
							&(var->datatype->typinput),
							var->datatype->typioparam,
							var->datatype->atttypmod, isnull);
	if (isnull)
		ereport(ERROR,
				(errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
				 errmsg("lower bound of FOR loop cannot be NULL")));
	var->value = value;
	var->isnull = false;
	exec_eval_cleanup(estate);

	/*
	 * Get the value of the upper bound
	 */
	value = exec_eval_expr(estate, stmt->upper, &isnull, &valtype);
	value = exec_cast_value(value, valtype, var->datatype->typoid,
							&(var->datatype->typinput),
							var->datatype->typioparam,
							var->datatype->atttypmod, isnull);
	if (isnull)
		ereport(ERROR,
				(errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
				 errmsg("upper bound of FOR loop cannot be NULL")));
	exec_eval_cleanup(estate);

	/*
	 * Get the by value
	 */
	by_value = exec_eval_expr(estate, stmt->by, &isnull, &valtype);
	by_value = exec_cast_value(by_value, valtype, var->datatype->typoid,
							   &(var->datatype->typinput),
							   var->datatype->typioparam,
							   var->datatype->atttypmod, isnull);

	if (isnull)
		ereport(ERROR,
				(errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
				 errmsg("by value of FOR loop cannot be NULL")));
	exec_eval_cleanup(estate);

	/*
	 * Now do the loop
	 */
	for (;;)
	{
		/*
		 * Check bounds
		 */
		if (stmt->reverse)
		{
			if ((int4) (var->value) < (int4) value)
				break;
		}
		else
		{
			if ((int4) (var->value) > (int4) value)
				break;
		}

		found = true;			/* looped at least once */

		/*
		 * Execute the statements
		 */
		rc = exec_stmts(estate, stmt->body);

		if (rc == PLPGSQL_RC_RETURN)
			break;				/* return from function */
		else if (rc == PLPGSQL_RC_EXIT)
		{
			if (estate->exitlabel == NULL)
				/* unlabelled exit, finish the current loop */
				rc = PLPGSQL_RC_OK;
			else if (stmt->label != NULL &&
					 strcmp(stmt->label, estate->exitlabel) == 0)
			{
				/* labelled exit, matches the current stmt's label */
				estate->exitlabel = NULL;
				rc = PLPGSQL_RC_OK;
			}

			/*
			 * otherwise, this is a labelled exit that does not match the
			 * current statement's label, if any: return RC_EXIT so that the
			 * EXIT continues to propagate up the stack.
			 */
			break;
		}
		else if (rc == PLPGSQL_RC_CONTINUE)
		{
			if (estate->exitlabel == NULL)
				/* unlabelled continue, so re-run the current loop */
				rc = PLPGSQL_RC_OK;
			else if (stmt->label != NULL &&
					 strcmp(stmt->label, estate->exitlabel) == 0)
			{
				/* label matches named continue, so re-run loop */
				estate->exitlabel = NULL;
				rc = PLPGSQL_RC_OK;
			}
			else
			{
				/*
				 * otherwise, this is a named continue that does not match the
				 * current statement's label, if any: return RC_CONTINUE so
				 * that the CONTINUE will propagate up the stack.
				 */
				break;
			}
		}

		/*
		 * Increase/decrease loop value, unless it would overflow, in which
		 * case exit the loop.
		 */
		if (stmt->reverse)
			var->value -= by_value;
		else
			var->value += by_value;
	}

	/*
	 * Set the FOUND variable to indicate the result of executing the loop
	 * (namely, whether we looped one or more times). This must be set here so
	 * that it does not interfere with the value of the FOUND variable inside
	 * the loop processing itself.
	 */
	exec_set_found(estate, found);

	return rc;
}


/* ----------
 * exec_stmt_fors			Execute a query, assign each
 *					tuple to a record or row and
 *					execute a group of statements
 *					for it.
 * ----------
 */
static int
exec_stmt_fors(PLpgSQL_execstate *estate, PLpgSQL_stmt_fors *stmt)
{
	PLpgSQL_rec *rec = NULL;
	PLpgSQL_row *row = NULL;
	SPITupleTable *tuptab;
	Portal		portal;
	bool		found = false;
	int			rc = PLPGSQL_RC_OK;
	int			i;
	int			n;

	/*
	 * Determine if we assign to a record or a row
	 */
	if (stmt->rec != NULL)
		rec = (PLpgSQL_rec *) (estate->datums[stmt->rec->recno]);
	else if (stmt->row != NULL)
		row = (PLpgSQL_row *) (estate->datums[stmt->row->rowno]);
	else
		elog(ERROR, "unsupported target");

	/*
	 * Open the implicit cursor for the statement and fetch the initial 10
	 * rows.
	 */
	exec_run_select(estate, stmt->query, 0, &portal);

	SPI_cursor_fetch(portal, true, 10);
	tuptab = SPI_tuptable;
	n = SPI_processed;

	/*
	 * If the query didn't return any rows, set the target to NULL and return
	 * with FOUND = false.
	 */
	if (n == 0)
		exec_move_row(estate, rec, row, NULL, tuptab->tupdesc);
	else
		found = true;			/* processed at least one tuple */

	/*
	 * Now do the loop
	 */
	while (n > 0)
	{
		for (i = 0; i < n; i++)
		{
			/*
			 * Assign the tuple to the target
			 */
			exec_move_row(estate, rec, row, tuptab->vals[i], tuptab->tupdesc);

			/*
			 * Execute the statements
			 */
			rc = exec_stmts(estate, stmt->body);
			if (rc != PLPGSQL_RC_OK)
			{
				if (rc == PLPGSQL_RC_EXIT)
				{
					if (estate->exitlabel == NULL)
						/* unlabelled exit, finish the current loop */
						rc = PLPGSQL_RC_OK;
					else if (stmt->label != NULL &&
							 strcmp(stmt->label, estate->exitlabel) == 0)
					{
						/* labelled exit, matches the current stmt's label */
						estate->exitlabel = NULL;
						rc = PLPGSQL_RC_OK;
					}

					/*
					 * otherwise, we processed a labelled exit that does not
					 * match the current statement's label, if any: return
					 * RC_EXIT so that the EXIT continues to recurse upward.
					 */
				}
				else if (rc == PLPGSQL_RC_CONTINUE)
				{
					if (estate->exitlabel == NULL)
					{
						/* anonymous continue, so re-run the current loop */
						rc = PLPGSQL_RC_OK;
						continue;
					}
					else if (stmt->label != NULL &&
							 strcmp(stmt->label, estate->exitlabel) == 0)
					{
						/* label matches named continue, so re-run loop */
						rc = PLPGSQL_RC_OK;
						estate->exitlabel = NULL;
						continue;
					}

					/*
					 * otherwise, we processed a named continue that does not
					 * match the current statement's label, if any: return
					 * RC_CONTINUE so that the CONTINUE will propagate up the
					 * stack.
					 */
				}

				/*
				 * We're aborting the loop, so cleanup and set FOUND. (This
				 * code should match the code after the loop.)
				 */
				SPI_freetuptable(tuptab);
				SPI_cursor_close(portal);
				exec_set_found(estate, found);

				return rc;
			}
		}

		SPI_freetuptable(tuptab);

		/*
		 * Fetch the next 50 tuples
		 */
		SPI_cursor_fetch(portal, true, 50);
		n = SPI_processed;
		tuptab = SPI_tuptable;
	}

	/*
	 * Release last group of tuples
	 */
	SPI_freetuptable(tuptab);

	/*
	 * Close the implicit cursor
	 */
	SPI_cursor_close(portal);

	/*
	 * Set the FOUND variable to indicate the result of executing the loop
	 * (namely, whether we looped one or more times). This must be set here so
	 * that it does not interfere with the value of the FOUND variable inside
	 * the loop processing itself.
	 */
	exec_set_found(estate, found);

	return rc;
}


/* ----------
 * exec_stmt_exit			Implements EXIT and CONTINUE
 *
 * This begins the process of exiting / restarting a loop.
 * ----------
 */
static int
exec_stmt_exit(PLpgSQL_execstate *estate, PLpgSQL_stmt_exit *stmt)
{
	/*
	 * If the exit / continue has a condition, evaluate it
	 */
	if (stmt->cond != NULL)
	{
		bool		value;
		bool		isnull;

		value = exec_eval_boolean(estate, stmt->cond, &isnull);
		exec_eval_cleanup(estate);
		if (isnull || value == false)
			return PLPGSQL_RC_OK;
	}

	estate->exitlabel = stmt->label;
	if (stmt->is_exit)
		return PLPGSQL_RC_EXIT;
	else
		return PLPGSQL_RC_CONTINUE;
}


/* ----------
 * exec_stmt_return			Evaluate an expression and start
 *					returning from the function.
 * ----------
 */
static int
exec_stmt_return(PLpgSQL_execstate *estate, PLpgSQL_stmt_return *stmt)
{
	/*
	 * If processing a set-returning PL/PgSQL function, the final RETURN
	 * indicates that the function is finished producing tuples.  The rest of
	 * the work will be done at the top level.
	 */
	if (estate->retisset)
		return PLPGSQL_RC_RETURN;

	/* initialize for null result (possibly a tuple) */
	estate->retval = (Datum) 0;
	estate->rettupdesc = NULL;
	estate->retisnull = true;

	if (stmt->retvarno >= 0)
	{
		PLpgSQL_datum *retvar = estate->datums[stmt->retvarno];

		switch (retvar->dtype)
		{
			case PLPGSQL_DTYPE_VAR:
				{
					PLpgSQL_var *var = (PLpgSQL_var *) retvar;

					estate->retval = var->value;
					estate->retisnull = var->isnull;
					estate->rettype = var->datatype->typoid;
				}
				break;

			case PLPGSQL_DTYPE_REC:
				{
					PLpgSQL_rec *rec = (PLpgSQL_rec *) retvar;

					if (HeapTupleIsValid(rec->tup))
					{
						estate->retval = PointerGetDatum(rec->tup);
						estate->rettupdesc = rec->tupdesc;
						estate->retisnull = false;
					}
				}
				break;

			case PLPGSQL_DTYPE_ROW:
				{
					PLpgSQL_row *row = (PLpgSQL_row *) retvar;

					Assert(row->rowtupdesc);
					estate->retval = PointerGetDatum(make_tuple_from_row(estate, row,
															row->rowtupdesc));
					if (estate->retval == 0) /* should not happen */
						elog(ERROR, "row not compatible with its own tupdesc");
					estate->rettupdesc = row->rowtupdesc;
					estate->retisnull = false;
				}
				break;

			default:
				elog(ERROR, "unrecognized dtype: %d", retvar->dtype);
		}

		return PLPGSQL_RC_RETURN;
	}

	if (stmt->expr != NULL)
	{
		if (estate->retistuple)
		{
			exec_run_select(estate, stmt->expr, 1, NULL);
			if (estate->eval_processed > 0)
			{
				estate->retval = PointerGetDatum(estate->eval_tuptable->vals[0]);
				estate->rettupdesc = estate->eval_tuptable->tupdesc;
				estate->retisnull = false;
			}
		}
		else
		{
			/* Normal case for scalar results */
			estate->retval = exec_eval_expr(estate, stmt->expr,
											&(estate->retisnull),
											&(estate->rettype));
		}

		return PLPGSQL_RC_RETURN;
	}

	/*
	 * Special hack for function returning VOID: instead of NULL, return a
	 * non-null VOID value.  This is of dubious importance but is kept for
	 * backwards compatibility.  Note that the only other way to get here is
	 * to have written "RETURN NULL" in a function returning tuple.
	 */
	if (estate->fn_rettype == VOIDOID)
	{
		estate->retval = (Datum) 0;
		estate->retisnull = false;
		estate->rettype = VOIDOID;
	}

	return PLPGSQL_RC_RETURN;
}

/* ----------
 * exec_stmt_return_next		Evaluate an expression and add it to the
 *								list of tuples returned by the current
 *								SRF.
 * ----------
 */
static int
exec_stmt_return_next(PLpgSQL_execstate *estate,
					  PLpgSQL_stmt_return_next *stmt)
{
	TupleDesc	tupdesc;
	int			natts;
	HeapTuple	tuple;
	bool		free_tuple = false;

	if (!estate->retisset)
		ereport(ERROR,
				(errcode(ERRCODE_SYNTAX_ERROR),
				 errmsg("cannot use RETURN NEXT in a non-SETOF function")));

	if (estate->tuple_store == NULL)
	{
		exec_init_tuple_store(estate);
	}

	/* rettupdesc will be filled by exec_init_tuple_store */
	tupdesc = estate->rettupdesc;
	natts = tupdesc->natts;

	if (stmt->retvarno >= 0)
	{
		PLpgSQL_datum *retvar = estate->datums[stmt->retvarno];

		switch (retvar->dtype)
		{
			case PLPGSQL_DTYPE_VAR:
				{
					PLpgSQL_var *var = (PLpgSQL_var *) retvar;
					Datum		retval = var->value;
					bool		isNull = var->isnull;

					if (natts != 1)
						ereport(ERROR,
								(errcode(ERRCODE_DATATYPE_MISMATCH),
						errmsg("wrong result type supplied in RETURN NEXT")));

					/* coerce type if needed */
					retval = exec_simple_cast_value(retval,
													var->datatype->typoid,
												 tupdesc->attrs[0]->atttypid,
												tupdesc->attrs[0]->atttypmod,
													isNull);

					tuple = heap_form_tuple(tupdesc, &retval, &isNull);

					free_tuple = true;
				}
				break;

			case PLPGSQL_DTYPE_REC:
				{
					PLpgSQL_rec *rec = (PLpgSQL_rec *) retvar;

					if (!HeapTupleIsValid(rec->tup))
						ereport(ERROR,
						  (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
						   errmsg("record \"%s\" is not assigned yet",
								  rec->refname),
						   errdetail("The tuple structure of a not-yet-assigned record is indeterminate.")));
					if (!compatible_tupdesc(tupdesc, rec->tupdesc))
						ereport(ERROR,
								(errcode(ERRCODE_DATATYPE_MISMATCH),
						errmsg("wrong record type supplied in RETURN NEXT")));
					tuple = rec->tup;
				}
				break;

			case PLPGSQL_DTYPE_ROW:
				{
					PLpgSQL_row *row = (PLpgSQL_row *) retvar;

					tuple = make_tuple_from_row(estate, row, tupdesc);
					if (tuple == NULL)
						ereport(ERROR,
								(errcode(ERRCODE_DATATYPE_MISMATCH),
						errmsg("wrong record type supplied in RETURN NEXT")));
					free_tuple = true;
				}
				break;

			default:
				elog(ERROR, "unrecognized dtype: %d", retvar->dtype);
				tuple = NULL;	/* keep compiler quiet */
				break;
		}
	}
	else if (stmt->expr)
	{
		Datum		retval;
		bool		isNull;
		Oid			rettype;

		if (natts != 1)
			ereport(ERROR,
					(errcode(ERRCODE_DATATYPE_MISMATCH),
					 errmsg("wrong result type supplied in RETURN NEXT")));

		retval = exec_eval_expr(estate,
								stmt->expr,
								&isNull,
								&rettype);

		/* coerce type if needed */
		retval = exec_simple_cast_value(retval,
										rettype,
										tupdesc->attrs[0]->atttypid,
										tupdesc->attrs[0]->atttypmod,
										isNull);

		tuple = heap_form_tuple(tupdesc, &retval, &isNull);

		free_tuple = true;

		exec_eval_cleanup(estate);
	}
	else
	{
		ereport(ERROR,
				(errcode(ERRCODE_SYNTAX_ERROR),
				 errmsg("RETURN NEXT must have a parameter")));
		tuple = NULL;			/* keep compiler quiet */
	}

	if (HeapTupleIsValid(tuple))
	{
		MemoryContext oldcxt;

		oldcxt = MemoryContextSwitchTo(estate->tuple_store_cxt);
		tuplestore_puttuple(estate->tuple_store, tuple);
		MemoryContextSwitchTo(oldcxt);

		if (free_tuple)
			heap_freetuple(tuple);
	}

	return PLPGSQL_RC_OK;
}

static void
exec_init_tuple_store(PLpgSQL_execstate *estate)
{
	ReturnSetInfo *rsi = estate->rsi;
	MemoryContext oldcxt;

	/*
	 * Check caller can handle a set result in the way we want
	 */
	if (!rsi || !IsA(rsi, ReturnSetInfo) ||
		(rsi->allowedModes & SFRM_Materialize) == 0 ||
		rsi->expectedDesc == NULL)
		ereport(ERROR,
				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
				 errmsg("set-valued function called in context that cannot accept a set")));

	estate->tuple_store_cxt = rsi->econtext->ecxt_per_query_memory;

	oldcxt = MemoryContextSwitchTo(estate->tuple_store_cxt);
	estate->tuple_store = tuplestore_begin_heap(true, false, work_mem); 
	MemoryContextSwitchTo(oldcxt);

	estate->rettupdesc = rsi->expectedDesc;
}

/* ----------
 * exec_stmt_raise			Build a message and throw it with elog()
 * ----------
 */
static int
exec_stmt_raise(PLpgSQL_execstate *estate, PLpgSQL_stmt_raise *stmt)
{
	char	   *cp;
	PLpgSQL_dstring ds;
	ListCell   *current_param;

	plpgsql_dstring_init(&ds);
	current_param = list_head(stmt->params);

	for (cp = stmt->message; *cp; cp++)
	{
		/*
		 * Occurrences of a single % are replaced by the next parameter's
		 * external representation. Double %'s are converted to one %.
		 */
		if (cp[0] == '%')
		{
			Oid			paramtypeid;
			Datum		paramvalue;
			bool		paramisnull;
			char	   *extval;

			if (cp[1] == '%')
			{
				plpgsql_dstring_append_char(&ds, cp[1]);
				cp++;
				continue;
			}

			if (current_param == NULL)
				ereport(ERROR,
						(errcode(ERRCODE_SYNTAX_ERROR),
						 errmsg("too few parameters specified for RAISE")));

			paramvalue = exec_eval_expr(estate,
									  (PLpgSQL_expr *) lfirst(current_param),
										&paramisnull,
										&paramtypeid);

			if (paramisnull)
				extval = "<NULL>";
			else
				extval = convert_value_to_string(paramvalue, paramtypeid);
			plpgsql_dstring_append(&ds, extval);
			current_param = lnext(current_param);
			exec_eval_cleanup(estate);
			continue;
		}

		plpgsql_dstring_append_char(&ds, cp[0]);
	}

	/*
	 * If more parameters were specified than were required to process the
	 * format string, throw an error
	 */
	if (current_param != NULL)
		ereport(ERROR,
				(errcode(ERRCODE_SYNTAX_ERROR),
				 errmsg("too many parameters specified for RAISE")));

	/*
	 * Throw the error (may or may not come back)
	 */
	estate->err_text = raise_skip_msg;	/* suppress traceback of raise */

	ereport(stmt->elog_level,
		 ((stmt->elog_level >= ERROR) ? errcode(ERRCODE_RAISE_EXCEPTION) : 0,
		  errmsg_internal("%s", plpgsql_dstring_get(&ds))));

	estate->err_text = NULL;	/* un-suppress... */

	plpgsql_dstring_free(&ds);

	return PLPGSQL_RC_OK;
}


/* ----------
 * Initialize a mostly empty execution state
 * ----------
 */
static void
plpgsql_estate_setup(PLpgSQL_execstate *estate,
					 PLpgSQL_function *func,
					 ReturnSetInfo *rsi)
{
	estate->retval = (Datum) 0;
	estate->retisnull = true;
	estate->rettype = InvalidOid;

	estate->fn_rettype = func->fn_rettype;
	estate->retistuple = func->fn_retistuple;
	estate->retisset = func->fn_retset;

	estate->readonly_func = func->fn_readonly;

	estate->rettupdesc = NULL;
	estate->exitlabel = NULL;

	estate->tuple_store = NULL;
	estate->tuple_store_cxt = NULL;
	estate->rsi = rsi;

	estate->trig_nargs = 0;
	estate->trig_argv = NULL;

	estate->found_varno = func->found_varno;
	estate->ndatums = func->ndatums;
	estate->datums = palloc(sizeof(PLpgSQL_datum *) * estate->ndatums);
	/* caller is expected to fill the datums array */

	estate->eval_tuptable = NULL;
	estate->eval_processed = 0;
	estate->eval_lastoid = InvalidOid;

	estate->err_func = func;
	estate->err_stmt = NULL;
	estate->err_text = NULL;

	/*
	 * Create an EState and ExprContext for evaluation of simple expressions.
	 */
	plpgsql_create_econtext(estate);

	/*
	 * Let the plugin see this function before we initialize any local
	 * PL/pgSQL variables - note that we also give the plugin a few function
	 * pointers so it can call back into PL/pgSQL for doing things like
	 * variable assignments and stack traces
	 */
	if (*plugin_ptr)
	{
		(*plugin_ptr)->error_callback = plpgsql_exec_error_callback;
		(*plugin_ptr)->assign_expr = exec_assign_expr;

		if ((*plugin_ptr)->func_setup)
			((*plugin_ptr)->func_setup) (estate, func);
	}
}

/* ----------
 * Release temporary memory used by expression/subselect evaluation
 *
 * NB: the result of the evaluation is no longer valid after this is done,
 * unless it is a pass-by-value datatype.
 * ----------
 */
static void
exec_eval_cleanup(PLpgSQL_execstate *estate)
{
	/* Clear result of a full SPI_execute */
	if (estate->eval_tuptable != NULL)
		SPI_freetuptable(estate->eval_tuptable);
	estate->eval_tuptable = NULL;

	/* Clear result of exec_eval_simple_expr (but keep the econtext) */
	if (estate->eval_econtext != NULL)
		ResetExprContext(estate->eval_econtext);
}


/* ----------
 * Generate a prepared plan
 * ----------
 */
static void
exec_prepare_plan(PLpgSQL_execstate *estate,
				  PLpgSQL_expr *expr)
{
	int			i;
	_SPI_plan  *spi_plan;
	void	   *plan;
	Oid		   *argtypes;

	/*
	 * We need a temporary argtypes array to load with data. (The finished
	 * plan structure will contain a copy of it.)
	 */
	argtypes = (Oid *) palloc(expr->nparams * sizeof(Oid));

	for (i = 0; i < expr->nparams; i++)
	{
		Datum		paramval;
		bool		paramisnull;

		exec_eval_datum(estate, estate->datums[expr->params[i]],
						InvalidOid,
						&argtypes[i], &paramval, &paramisnull);
	}

	/*
	 * Generate and save the plan
	 */
	plan = SPI_prepare(expr->query, expr->nparams, argtypes);
	if (plan == NULL)
	{
		/* Some SPI errors deserve specific error messages */
		switch (SPI_result)
		{
			case SPI_ERROR_COPY:
				ereport(ERROR,
						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
						 errmsg("cannot COPY to/from client in PL/pgSQL")));
			case SPI_ERROR_CURSOR:
				ereport(ERROR,
						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
					errmsg("cannot manipulate cursors directly in PL/pgSQL"),
						 errhint("Use PL/pgSQL's cursor features instead.")));
			case SPI_ERROR_TRANSACTION:
				ereport(ERROR,
						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
						 errmsg("cannot begin/end transactions in PL/pgSQL"),
						 errhint("Use a BEGIN block with an EXCEPTION clause instead.")));
			default:
				elog(ERROR, "SPI_prepare failed for \"%s\": %s",
					 expr->query, SPI_result_code_string(SPI_result));
		}
	}
	expr->plan = SPI_saveplan(plan);
	spi_plan = (_SPI_plan *) expr->plan;
	expr->plan_argtypes = spi_plan->argtypes;
	expr->expr_simple_expr = NULL;
	exec_simple_check_plan(expr);

	SPI_freeplan(plan);

	if (Gp_role != GP_ROLE_EXECUTE)
	{
		/* 
		 * if we are not in EXECUTE mode, check if plan should be cached. 
		 */
		exec_check_cache_plan(expr);
	}

	pfree(argtypes);
}


/* ----------
 * exec_stmt_execsql			Execute an SQL statement (possibly with INTO).
 * ----------
 */
static int
exec_stmt_execsql(PLpgSQL_execstate *estate,
				  PLpgSQL_stmt_execsql *stmt)
{
	int			i;
	Datum	   *values;
	char	   *nulls;
	long		tcount;
	int			rc;
	PLpgSQL_expr *expr = stmt->sqlstmt;

	/*
	 * On the first call for this statement generate the plan, and detect
	 * whether the statement is INSERT/UPDATE/DELETE
	 */

 	/* if we find a cached plan, check if we want to use it */
	if (expr->plan != NULL)
	{
		exec_free_plan(expr);
	}
	
	if (expr->plan == NULL)
	{
		_SPI_plan  *spi_plan;
		ListCell   *l;

		exec_prepare_plan(estate, expr);
		stmt->mod_stmt = false;
		spi_plan = (_SPI_plan *) expr->plan;
		foreach(l, spi_plan->qtlist)
		{
			ListCell   *l2;

			foreach(l2, (List *) lfirst(l))
			{
				Query	   *q = (Query *) lfirst(l2);

				Assert(IsA(q, Query));
				if (q->canSetTag)
				{
					if (q->commandType == CMD_INSERT ||
						q->commandType == CMD_UPDATE ||
						q->commandType == CMD_DELETE)
						stmt->mod_stmt = true;
				}
			}
		}
	}

	/*
	 * Now build up the values and nulls arguments for SPI_execute_plan()
	 */
	values = (Datum *) palloc(expr->nparams * sizeof(Datum));
	nulls = (char *) palloc(expr->nparams * sizeof(char));

	for (i = 0; i < expr->nparams; i++)
	{
		PLpgSQL_datum *datum = estate->datums[expr->params[i]];
		Oid			paramtypeid;
		bool		paramisnull;

		exec_eval_datum(estate, datum, expr->plan_argtypes[i],
						&paramtypeid, &values[i], &paramisnull);
		if (paramisnull)
			nulls[i] = 'n';
		else
			nulls[i] = ' ';
	}

	/*
	 * If we have INTO, then we only need one row back ... but if we have INTO
	 * STRICT, ask for two rows, so that we can verify the statement returns
	 * only one.  INSERT/UPDATE/DELETE are always treated strictly. Without
	 * INTO, just run the statement to completion (tcount = 0).
	 *
	 * We could just ask for two rows always when using INTO, but there are
	 * some cases where demanding the extra row costs significant time, eg by
	 * forcing completion of a sequential scan.  So don't do it unless we need
	 * to enforce strictness.
	 */
	if (stmt->into)
	{
		if (stmt->strict || stmt->mod_stmt)
			tcount = 2;
		else
			tcount = 1;
	}
	else
		tcount = 0;

	/*
	 * Execute the plan
	 */
	rc = SPI_execute_plan(expr->plan, values, nulls,
						  estate->readonly_func, tcount);

	/*
	 * Check for error, and set FOUND if appropriate (for historical reasons
	 * we set FOUND only for certain query types).	Also Assert that we
	 * identified the statement type the same as SPI did.
	 */
	switch (rc)
	{
		case SPI_OK_SELECT:
			Assert(!stmt->mod_stmt);
			exec_set_found(estate, (SPI_processed != 0));
			break;

		case SPI_OK_INSERT:
		case SPI_OK_UPDATE:
		case SPI_OK_DELETE:
		case SPI_OK_INSERT_RETURNING:
		case SPI_OK_UPDATE_RETURNING:
		case SPI_OK_DELETE_RETURNING:
			Assert(stmt->mod_stmt);
			exec_set_found(estate, (SPI_processed != 0));
			break;

		case SPI_OK_SELINTO:
		case SPI_OK_UTILITY:
			Assert(!stmt->mod_stmt);
			break;

		case SPI_OK_REWRITTEN:
			Assert(!stmt->mod_stmt);

			/*
			 * The command was rewritten into another kind of command. It's
			 * not clear what FOUND would mean in that case (and SPI doesn't
			 * return the row count either), so just set it to false.
			 */
			exec_set_found(estate, false);
			break;

			/* Some SPI errors deserve specific error messages */
		case SPI_ERROR_COPY:
			ereport(ERROR,
					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
					 errmsg("cannot COPY to/from client in PL/pgSQL")));

			/* Fixes MPP-3344 */
		case SPI_ERROR_TRANSACTION:
			ereport(ERROR,
					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
					 errmsg("cannot begin/end transactions in PL/pgSQL"),
			errhint("Use a BEGIN block with an EXCEPTION clause instead.")));
			break;

		default:
			elog(ERROR, "SPI_execute_plan failed executing query \"%s\": %s",
				 expr->query, SPI_result_code_string(rc));
	}

	/* All variants should save result info for GET DIAGNOSTICS */
	estate->eval_processed = SPI_processed64;
	estate->eval_lastoid = SPI_lastoid;

	/* Process INTO if present */
	if (stmt->into)
	{
		SPITupleTable *tuptab = SPI_tuptable;
		uint32		n = SPI_processed;
		PLpgSQL_rec *rec = NULL;
		PLpgSQL_row *row = NULL;

		/* If the statement did not return a tuple table, complain */
		if (tuptab == NULL)
			ereport(ERROR,
					(errcode(ERRCODE_SYNTAX_ERROR),
				errmsg("INTO used with a command that cannot return data")));

		/* Determine if we assign to a record or a row */
		if (stmt->rec != NULL)
			rec = (PLpgSQL_rec *) (estate->datums[stmt->rec->recno]);
		else if (stmt->row != NULL)
			row = (PLpgSQL_row *) (estate->datums[stmt->row->rowno]);
		else
			elog(ERROR, "unsupported target");

		/*
		 * If SELECT ... INTO specified STRICT, and the query didn't find
		 * exactly one row, throw an error.  If STRICT was not specified, then
		 * allow the query to find any number of rows.
		 */
		if (n == 0)
		{
			if (stmt->strict)
				ereport(ERROR,
						(errcode(ERRCODE_NO_DATA_FOUND),
						 errmsg("query returned no rows")));
			/* set the target to NULL(s) */
			exec_move_row(estate, rec, row, NULL, tuptab->tupdesc);
		}
		else
		{
			if (n > 1 && (stmt->strict || stmt->mod_stmt))
				ereport(ERROR,
						(errcode(ERRCODE_TOO_MANY_ROWS),
						 errmsg("query returned more than one row")));
			/* Put the first result row into the target */
			exec_move_row(estate, rec, row, tuptab->vals[0], tuptab->tupdesc);
		}

		/* Clean up */
		SPI_freetuptable(SPI_tuptable);
	}
	else
	{
		/* If the statement returned a tuple table, complain */
		if (SPI_tuptable != NULL)
			ereport(ERROR,
					(errcode(ERRCODE_SYNTAX_ERROR),
					 errmsg("query has no destination for result data"),
					 (rc == SPI_OK_SELECT) ? errhint("If you want to discard the results of a SELECT, use PERFORM instead.") : 0));
	}

	pfree(values);
	pfree(nulls);

	return PLPGSQL_RC_OK;
}


/* ----------
 * exec_stmt_dynexecute			Execute a dynamic SQL query
 *					(possibly with INTO).
 * ----------
 */
static int
exec_stmt_dynexecute(PLpgSQL_execstate *estate,
					 PLpgSQL_stmt_dynexecute *stmt)
{
	Datum		query;
	bool		isnull = false;
	Oid			restype;
	char	   *querystr;
	int			exec_res;

	/*
	 * First we evaluate the string expression after the EXECUTE keyword. Its
	 * result is the querystring we have to execute.
	 */
	query = exec_eval_expr(estate, stmt->query, &isnull, &restype);
	if (isnull)
		ereport(ERROR,
				(errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
				 errmsg("cannot EXECUTE a null querystring")));

	/* Get the C-String representation */
	querystr = convert_value_to_string(query, restype);

	exec_eval_cleanup(estate);

	/*
	 * Call SPI_execute() without preparing a saved plan.
	 */
	exec_res = SPI_execute(querystr, estate->readonly_func, 0);

	switch (exec_res)
	{
		case SPI_OK_SELECT:
		case SPI_OK_INSERT:
		case SPI_OK_UPDATE:
		case SPI_OK_DELETE:
		case SPI_OK_INSERT_RETURNING:
		case SPI_OK_UPDATE_RETURNING:
		case SPI_OK_DELETE_RETURNING:
		case SPI_OK_UTILITY:
			break;

		case 0:

			/*
			 * Also allow a zero return, which implies the querystring
			 * contained no commands.
			 */
			break;

		case SPI_OK_SELINTO:

			/*
			 * We want to disallow SELECT INTO for now, because its behavior
			 * is not consistent with SELECT INTO in a normal plpgsql context.
			 * (We need to reimplement EXECUTE to parse the string as a
			 * plpgsql command, not just feed it to SPI_execute.) However,
			 * CREATE AS should be allowed ... and since it produces the same
			 * parsetree as SELECT INTO, there's no way to tell the difference
			 * except to look at the source text.  Wotta kluge!
			 */
			{
				char	   *ptr;

				for (ptr = querystr; *ptr; ptr++)
					if (!scanner_isspace(*ptr))
						break;
				if (*ptr == 'S' || *ptr == 's')
					ereport(ERROR,
							(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
							 errmsg("EXECUTE of SELECT ... INTO is not implemented yet")));
				break;
			}

			/* Some SPI errors deserve specific error messages */
		case SPI_ERROR_COPY:
			ereport(ERROR,
					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
					 errmsg("cannot COPY to/from client in PL/pgSQL")));
		case SPI_ERROR_CURSOR:
			ereport(ERROR,
					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
					 errmsg("cannot manipulate cursors directly in PL/pgSQL"),
					 errhint("Use PL/pgSQL's cursor features instead.")));
		case SPI_ERROR_TRANSACTION:
			ereport(ERROR,
					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
					 errmsg("cannot begin/end transactions in PL/pgSQL"),
			errhint("Use a BEGIN block with an EXCEPTION clause instead.")));

		default:
			elog(ERROR, "SPI_execute failed executing query \"%s\": %s",
				 querystr, SPI_result_code_string(exec_res));
			break;
	}

	/* Save result info for GET DIAGNOSTICS */
	estate->eval_processed = SPI_processed;
	estate->eval_lastoid = SPI_lastoid;

	/* Process INTO if present */
	if (stmt->into)
	{
		SPITupleTable *tuptab = SPI_tuptable;
		uint32		n = SPI_processed;
		PLpgSQL_rec *rec = NULL;
		PLpgSQL_row *row = NULL;

		/* If the statement did not return a tuple table, complain */
		if (tuptab == NULL)
			ereport(ERROR,
					(errcode(ERRCODE_SYNTAX_ERROR),
				errmsg("INTO used with a command that cannot return data")));

		/* Determine if we assign to a record or a row */
		if (stmt->rec != NULL)
			rec = (PLpgSQL_rec *) (estate->datums[stmt->rec->recno]);
		else if (stmt->row != NULL)
			row = (PLpgSQL_row *) (estate->datums[stmt->row->rowno]);
		else
			elog(ERROR, "unsupported target");

		/*
		 * If SELECT ... INTO specified STRICT, and the query didn't find
		 * exactly one row, throw an error.  If STRICT was not specified, then
		 * allow the query to find any number of rows.
		 */
		if (n == 0)
		{
			if (stmt->strict)
				ereport(ERROR,
						(errcode(ERRCODE_NO_DATA_FOUND),
						 errmsg("query returned no rows")));
			/* set the target to NULL(s) */
			exec_move_row(estate, rec, row, NULL, tuptab->tupdesc);
		}
		else
		{
			if (n > 1 && stmt->strict)
				ereport(ERROR,
						(errcode(ERRCODE_TOO_MANY_ROWS),
						 errmsg("query returned more than one row")));
			/* Put the first result row into the target */
			exec_move_row(estate, rec, row, tuptab->vals[0], tuptab->tupdesc);
		}
	}
	else
	{
		/*
		 * It might be a good idea to raise an error if the query returned
		 * tuples that are being ignored, but historically we have not done
		 * that.
		 */
	}

	/* Release any result from SPI_execute, as well as the querystring */
	SPI_freetuptable(SPI_tuptable);
	pfree(querystr);

	return PLPGSQL_RC_OK;
}


/* ----------
 * exec_stmt_dynfors			Execute a dynamic query, assign each
 *					tuple to a record or row and
 *					execute a group of statements
 *					for it.
 * ----------
 */
static int
exec_stmt_dynfors(PLpgSQL_execstate *estate, PLpgSQL_stmt_dynfors *stmt)
{
	Datum		query;
	bool		isnull;
	Oid			restype;
	char	   *querystr;
	PLpgSQL_rec *rec = NULL;
	PLpgSQL_row *row = NULL;
	SPITupleTable *tuptab;
	int			n;
	void	   *plan;
	Portal		portal;
	bool		found = false;

	/*
	 * Determine if we assign to a record or a row
	 */
	if (stmt->rec != NULL)
		rec = (PLpgSQL_rec *) (estate->datums[stmt->rec->recno]);
	else if (stmt->row != NULL)
		row = (PLpgSQL_row *) (estate->datums[stmt->row->rowno]);
	else
		elog(ERROR, "unsupported target");

	/*
	 * Evaluate the string expression after the EXECUTE keyword. It's result
	 * is the querystring we have to execute.
	 */
	query = exec_eval_expr(estate, stmt->query, &isnull, &restype);
	if (isnull)
		ereport(ERROR,
				(errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
				 errmsg("cannot EXECUTE a null querystring")));

	/* Get the C-String representation */
	querystr = convert_value_to_string(query, restype);

	exec_eval_cleanup(estate);

	/*
	 * Prepare a plan and open an implicit cursor for the query
	 */
	plan = SPI_prepare(querystr, 0, NULL);
	if (plan == NULL)
		elog(ERROR, "SPI_prepare failed for \"%s\": %s",
			 querystr, SPI_result_code_string(SPI_result));
	portal = SPI_cursor_open(NULL, plan, NULL, NULL,
							 estate->readonly_func);
	if (portal == NULL)
		elog(ERROR, "could not open implicit cursor for query \"%s\": %s",
			 querystr, SPI_result_code_string(SPI_result));
	pfree(querystr);
	SPI_freeplan(plan);

	/*
	 * Fetch the initial 10 tuples
	 */
	SPI_cursor_fetch(portal, true, 10);
	tuptab = SPI_tuptable;
	n = SPI_processed;

	/*
	 * If the query didn't return any rows, set the target to NULL and return
	 * with FOUND = false.
	 */
	if (n == 0)
		exec_move_row(estate, rec, row, NULL, tuptab->tupdesc);
	else
		found = true;			/* processed at least one tuple */

	/*
	 * Now do the loop
	 */
	while (n > 0)
	{
		int			i;

		for (i = 0; i < n; i++)
		{
			int			rc;

			/*
			 * Assign the tuple to the target
			 */
			exec_move_row(estate, rec, row, tuptab->vals[i], tuptab->tupdesc);

			/*
			 * Execute the statements
			 */
			rc = exec_stmts(estate, stmt->body);

			if (rc != PLPGSQL_RC_OK)
			{
				if (rc == PLPGSQL_RC_EXIT)
				{
					if (estate->exitlabel == NULL)
						/* unlabelled exit, finish the current loop */
						rc = PLPGSQL_RC_OK;
					else if (stmt->label != NULL &&
							 strcmp(stmt->label, estate->exitlabel) == 0)
					{
						/* labelled exit, matches the current stmt's label */
						estate->exitlabel = NULL;
						rc = PLPGSQL_RC_OK;
					}

					/*
					 * otherwise, we processed a labelled exit that does not
					 * match the current statement's label, if any: return
					 * RC_EXIT so that the EXIT continues to recurse upward.
					 */
				}
				else if (rc == PLPGSQL_RC_CONTINUE)
				{
					if (estate->exitlabel == NULL)
						/* unlabelled continue, continue the current loop */
						continue;
					else if (stmt->label != NULL &&
							 strcmp(stmt->label, estate->exitlabel) == 0)
					{
						/* labelled continue, matches the current stmt's label */
						estate->exitlabel = NULL;
						continue;
					}

					/*
					 * otherwise, we process a labelled continue that does not
					 * match the current statement's label, so propagate
					 * RC_CONTINUE upward in the stack.
					 */
				}

				/*
				 * We're aborting the loop, so cleanup and set FOUND. (This
				 * code should match the code after the loop.)
				 */
				SPI_freetuptable(tuptab);
				SPI_cursor_close(portal);
				exec_set_found(estate, found);

				return rc;
			}
		}

		SPI_freetuptable(tuptab);

		/*
		 * Fetch the next 50 tuples
		 */
		SPI_cursor_fetch(portal, true, 50);
		n = SPI_processed;
		tuptab = SPI_tuptable;
	}

	/*
	 * Release last group of tuples
	 */
	SPI_freetuptable(tuptab);

	/*
	 * Close the implicit cursor
	 */
	SPI_cursor_close(portal);

	/*
	 * Set the FOUND variable to indicate the result of executing the loop
	 * (namely, whether we looped one or more times). This must be set here so
	 * that it does not interfere with the value of the FOUND variable inside
	 * the loop processing itself.
	 */
	exec_set_found(estate, found);

	return PLPGSQL_RC_OK;
}


/* ----------
 * exec_stmt_open			Execute an OPEN cursor statement
 * ----------
 */
static int
exec_stmt_open(PLpgSQL_execstate *estate, PLpgSQL_stmt_open *stmt)
{
	PLpgSQL_var *curvar = NULL;
	char	   *curname = NULL;
	PLpgSQL_expr *query = NULL;
	Portal		portal;
	int			i;
	Datum	   *values;
	char	   *nulls;
	bool		isnull;


	/* ----------
	 * Get the cursor variable and if it has an assigned name, check
	 * that it's not in use currently.
	 * ----------
	 */
	curvar = (PLpgSQL_var *) (estate->datums[stmt->curvar]);
	if (!curvar->isnull)
	{
		curname = DatumGetCString(DirectFunctionCall1(textout, curvar->value));
		if (SPI_cursor_find(curname) != NULL)
			ereport(ERROR,
					(errcode(ERRCODE_DUPLICATE_CURSOR),
					 errmsg("cursor \"%s\" already in use", curname)));
	}

	/* ----------
	 * Process the OPEN according to it's type.
	 * ----------
	 */
	if (stmt->query != NULL)
	{
		/* ----------
		 * This is an OPEN refcursor FOR SELECT ...
		 *
		 * We just make sure the query is planned. The real work is
		 * done downstairs.
		 * ----------
		 */
		query = stmt->query;

	 	/* if we find a cached plan, check if we want to use it */
		if (query->plan != NULL)
		{
			exec_free_plan(query);
		}
	
		if (query->plan == NULL)
			exec_prepare_plan(estate, query);
	}
	else if (stmt->dynquery != NULL)
	{
		/* ----------
		 * This is an OPEN refcursor FOR EXECUTE ...
		 * ----------
		 */
		Datum		queryD;
		Oid			restype;
		char	   *querystr;
		void	   *curplan;

		/* ----------
		 * We evaluate the string expression after the
		 * EXECUTE keyword. It's result is the querystring we have
		 * to execute.
		 * ----------
		 */
		queryD = exec_eval_expr(estate, stmt->dynquery, &isnull, &restype);
		if (isnull)
			ereport(ERROR,
					(errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
					 errmsg("cannot EXECUTE a null querystring")));

		/* Get the C-String representation */
		querystr = convert_value_to_string(queryD, restype);

		exec_eval_cleanup(estate);

		/* ----------
		 * Now we prepare a query plan for it and open a cursor
		 * ----------
		 */
		curplan = SPI_prepare(querystr, 0, NULL);
		if (curplan == NULL)
			elog(ERROR, "SPI_prepare failed for \"%s\": %s",
				 querystr, SPI_result_code_string(SPI_result));
		portal = SPI_cursor_open(curname, curplan, NULL, NULL,
								 estate->readonly_func);
		if (portal == NULL)
			elog(ERROR, "could not open cursor for query \"%s\": %s",
				 querystr, SPI_result_code_string(SPI_result));
		pfree(querystr);
		SPI_freeplan(curplan);

		/* ----------
		 * Store the eventually assigned cursor name in the cursor variable
		 * ----------
		 */
		free_var(curvar);
		curvar->value = DirectFunctionCall1(textin, CStringGetDatum((char *) portal->name));
		curvar->isnull = false;
		curvar->freeval = true;

		return PLPGSQL_RC_OK;
	}
	else
	{
		/* ----------
		 * This is an OPEN cursor
		 *
		 * Note: parser should already have checked that statement supplies
		 * args iff cursor needs them, but we check again to be safe.
		 * ----------
		 */
		if (stmt->argquery != NULL)
		{
			/* ----------
			 * OPEN CURSOR with args.  We fake a SELECT ... INTO ...
			 * statement to evaluate the args and put 'em into the
			 * internal row.
			 * ----------
			 */
			PLpgSQL_stmt_execsql set_args;

			if (curvar->cursor_explicit_argrow < 0)
				ereport(ERROR,
						(errcode(ERRCODE_SYNTAX_ERROR),
					errmsg("arguments given for cursor without arguments")));

			memset(&set_args, 0, sizeof(set_args));
			set_args.cmd_type = PLPGSQL_STMT_EXECSQL;
			set_args.lineno = stmt->lineno;
			set_args.sqlstmt = stmt->argquery;
			set_args.into = true;
			/* XXX historically this has not been STRICT */
			set_args.row = (PLpgSQL_row *)
				(estate->datums[curvar->cursor_explicit_argrow]);

			if (exec_stmt_execsql(estate, &set_args) != PLPGSQL_RC_OK)
				elog(ERROR, "open cursor failed during argument processing");
		}
		else
		{
			if (curvar->cursor_explicit_argrow >= 0)
				ereport(ERROR,
						(errcode(ERRCODE_SYNTAX_ERROR),
						 errmsg("arguments required for cursor")));
		}

		query = curvar->cursor_explicit_expr;
		/* if we find a cached plan, check if we want to use it */
		if (query->plan != NULL)
		{
			exec_free_plan(query);
		}

		if (query->plan == NULL)
			exec_prepare_plan(estate, query);
	}

	/* ----------
	 * Here we go if we have a saved plan where we have to put
	 * values into, either from an explicit cursor or from a
	 * refcursor opened with OPEN ... FOR SELECT ...;
	 * ----------
	 */
	values = (Datum *) palloc(query->nparams * sizeof(Datum));
	nulls = (char *) palloc(query->nparams * sizeof(char));

	for (i = 0; i < query->nparams; i++)
	{
		PLpgSQL_datum *datum = estate->datums[query->params[i]];
		Oid			paramtypeid;
		bool		paramisnull;

		exec_eval_datum(estate, datum, query->plan_argtypes[i],
						&paramtypeid, &values[i], &paramisnull);
		if (paramisnull)
			nulls[i] = 'n';
		else
			nulls[i] = ' ';
	}

	/* ----------
	 * Open the cursor
	 * ----------
	 */
	portal = SPI_cursor_open(curname, query->plan, values, nulls,
							 estate->readonly_func);
	if (portal == NULL)
		elog(ERROR, "could not open cursor: %s",
			 SPI_result_code_string(SPI_result));

	pfree(values);
	pfree(nulls);
	if (curname)
		pfree(curname);

	/* ----------
	 * Store the eventually assigned portal name in the cursor variable
	 * ----------
	 */
	free_var(curvar);
	curvar->value = DirectFunctionCall1(textin, CStringGetDatum((char *) portal->name));
	curvar->isnull = false;
	curvar->freeval = true;

	return PLPGSQL_RC_OK;
}


/* ----------
 * exec_stmt_fetch			Fetch from a cursor into a target
 * ----------
 */
static int
exec_stmt_fetch(PLpgSQL_execstate *estate, PLpgSQL_stmt_fetch *stmt)
{
	PLpgSQL_var *curvar = NULL;
	PLpgSQL_rec *rec = NULL;
	PLpgSQL_row *row = NULL;
	SPITupleTable *tuptab;
	Portal		portal;
	char	   *curname;
	int			n;

	/* ----------
	 * Get the portal of the cursor by name
	 * ----------
	 */
	curvar = (PLpgSQL_var *) (estate->datums[stmt->curvar]);
	if (curvar->isnull)
		ereport(ERROR,
				(errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
				 errmsg("cursor variable \"%s\" is NULL", curvar->refname)));
	curname = DatumGetCString(DirectFunctionCall1(textout, curvar->value));

	portal = SPI_cursor_find(curname);
	if (portal == NULL)
		ereport(ERROR,
				(errcode(ERRCODE_UNDEFINED_CURSOR),
				 errmsg("cursor \"%s\" does not exist", curname)));
	pfree(curname);

	/* ----------
	 * Determine if we fetch into a record or a row
	 * ----------
	 */
	if (stmt->rec != NULL)
		rec = (PLpgSQL_rec *) (estate->datums[stmt->rec->recno]);
	else if (stmt->row != NULL)
		row = (PLpgSQL_row *) (estate->datums[stmt->row->rowno]);
	else
		elog(ERROR, "unsupported target");

	/* ----------
	 * Fetch 1 tuple from the cursor
	 * ----------
	 */
	SPI_cursor_fetch(portal, true, 1);
	tuptab = SPI_tuptable;
	n = SPI_processed;

	/* ----------
	 * Set the target and the global FOUND variable appropriately.
	 * ----------
	 */
	if (n == 0)
	{
		exec_move_row(estate, rec, row, NULL, tuptab->tupdesc);
		exec_set_found(estate, false);
	}
	else
	{
		exec_move_row(estate, rec, row, tuptab->vals[0], tuptab->tupdesc);
		exec_set_found(estate, true);
	}

	SPI_freetuptable(tuptab);

	return PLPGSQL_RC_OK;
}


/* ----------
 * exec_stmt_close			Close a cursor
 * ----------
 */
static int
exec_stmt_close(PLpgSQL_execstate *estate, PLpgSQL_stmt_close *stmt)
{
	PLpgSQL_var *curvar = NULL;
	Portal		portal;
	char	   *curname;

	/* ----------
	 * Get the portal of the cursor by name
	 * ----------
	 */
	curvar = (PLpgSQL_var *) (estate->datums[stmt->curvar]);
	if (curvar->isnull)
		ereport(ERROR,
				(errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
				 errmsg("cursor variable \"%s\" is NULL", curvar->refname)));
	curname = DatumGetCString(DirectFunctionCall1(textout, curvar->value));

	portal = SPI_cursor_find(curname);
	if (portal == NULL)
		ereport(ERROR,
				(errcode(ERRCODE_UNDEFINED_CURSOR),
				 errmsg("cursor \"%s\" does not exist", curname)));
	pfree(curname);

	/* ----------
	 * And close it.
	 * ----------
	 */
	SPI_cursor_close(portal);

	return PLPGSQL_RC_OK;
}


/* ----------
 * exec_assign_expr			Put an expression's result into
 *					a variable.
 * ----------
 */
static void
exec_assign_expr(PLpgSQL_execstate *estate, PLpgSQL_datum *target,
				 PLpgSQL_expr *expr)
{
	Datum		value;
	Oid			valtype;
	bool		isnull = false;

	value = exec_eval_expr(estate, expr, &isnull, &valtype);
	exec_assign_value(estate, target, value, valtype, &isnull);
	exec_eval_cleanup(estate);
}


/* ----------
 * exec_assign_value			Put a value into a target field
 * ----------
 */
static void
exec_assign_value(PLpgSQL_execstate *estate,
				  PLpgSQL_datum *target,
				  Datum value, Oid valtype, bool *isNull)
{
	switch (target->dtype)
	{
		case PLPGSQL_DTYPE_VAR:
			{
				/*
				 * Target is a variable
				 */
				PLpgSQL_var *var = (PLpgSQL_var *) target;
				Datum		newvalue;

				newvalue = exec_cast_value(value, valtype, var->datatype->typoid,
										   &(var->datatype->typinput),
										   var->datatype->typioparam,
										   var->datatype->atttypmod,
										   *isNull);

				if (*isNull && var->notnull)
					ereport(ERROR,
							(errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
							 errmsg("null value cannot be assigned to variable \"%s\" declared NOT NULL",
									var->refname)));

				/*
				 * If type is by-reference, make sure we have a freshly
				 * palloc'd copy; the originally passed value may not live as
				 * long as the variable!  But we don't need to re-copy if
				 * exec_cast_value performed a conversion; its output must
				 * already be palloc'd.
				 */
				if (!var->datatype->typbyval && !*isNull)
				{
					if (newvalue == value)
						newvalue = datumCopy(newvalue,
											 false,
											 var->datatype->typlen);
				}

				/*
				 * Now free the old value.	(We can't do this any earlier
				 * because of the possibility that we are assigning the var's
				 * old value to it, eg "foo := foo".  We could optimize out
				 * the assignment altogether in such cases, but it's too
				 * infrequent to be worth testing for.)
				 */
				free_var(var);

				var->value = newvalue;
				var->isnull = *isNull;
				if (!var->datatype->typbyval && !*isNull)
					var->freeval = true;
				break;
			}

		case PLPGSQL_DTYPE_ROW:
			{
				/*
				 * Target is a row variable
				 */
				PLpgSQL_row *row = (PLpgSQL_row *) target;

				/* Source must be of RECORD or composite type */
				if (!(valtype == RECORDOID ||
					  get_typtype(valtype) == 'c'))
					ereport(ERROR,
							(errcode(ERRCODE_DATATYPE_MISMATCH),
							 errmsg("cannot assign non-composite value to a row variable")));
				if (*isNull)
				{
					/* If source is null, just assign nulls to the row */
					exec_move_row(estate, NULL, row, NULL, NULL);
				}
				else
				{
					HeapTupleHeader td;
					Oid			tupType;
					int32		tupTypmod;
					TupleDesc	tupdesc;
					HeapTupleData tmptup;

					/* Else source is a tuple Datum, safe to do this: */
					td = DatumGetHeapTupleHeader(value);
					/* Extract rowtype info and find a tupdesc */
					tupType = HeapTupleHeaderGetTypeId(td);
					tupTypmod = HeapTupleHeaderGetTypMod(td);
					tupdesc = lookup_rowtype_tupdesc(tupType, tupTypmod);
					/* Build a temporary HeapTuple control structure */
					tmptup.t_len = HeapTupleHeaderGetDatumLength(td);
					ItemPointerSetInvalid(&(tmptup.t_self));
					tmptup.t_data = td;
					exec_move_row(estate, NULL, row, &tmptup, tupdesc);
					ReleaseTupleDesc(tupdesc);
				}
				break;
			}

		case PLPGSQL_DTYPE_REC:
			{
				/*
				 * Target is a record variable
				 */
				PLpgSQL_rec *rec = (PLpgSQL_rec *) target;

				/* Source must be of RECORD or composite type */
				if (!(valtype == RECORDOID ||
					  get_typtype(valtype) == 'c'))
					ereport(ERROR,
							(errcode(ERRCODE_DATATYPE_MISMATCH),
							 errmsg("cannot assign non-composite value to a record variable")));
				if (*isNull)
				{
					/* If source is null, just assign nulls to the record */
					exec_move_row(estate, rec, NULL, NULL, NULL);
				}
				else
				{
					HeapTupleHeader td;
					Oid			tupType;
					int32		tupTypmod;
					TupleDesc	tupdesc;
					HeapTupleData tmptup;

					/* Else source is a tuple Datum, safe to do this: */
					td = DatumGetHeapTupleHeader(value);
					/* Extract rowtype info and find a tupdesc */
					tupType = HeapTupleHeaderGetTypeId(td);
					tupTypmod = HeapTupleHeaderGetTypMod(td);
					tupdesc = lookup_rowtype_tupdesc(tupType, tupTypmod);
					/* Build a temporary HeapTuple control structure */
					tmptup.t_len = HeapTupleHeaderGetDatumLength(td);
					ItemPointerSetInvalid(&(tmptup.t_self));
					tmptup.t_data = td;
					exec_move_row(estate, rec, NULL, &tmptup, tupdesc);
					ReleaseTupleDesc(tupdesc);
				}
				break;
			}

		case PLPGSQL_DTYPE_RECFIELD:
			{
				/*
				 * Target is a field of a record
				 */
				PLpgSQL_recfield *recfield = (PLpgSQL_recfield *) target;
				PLpgSQL_rec *rec;
				int			fno;
				HeapTuple	newtup;
				int			natts;
				int			i;
				Datum	   *values;
				bool	   *nulls;
				void	   *mustfree;
				bool		attisnull;
				Oid			atttype;
				int32		atttypmod;

				rec = (PLpgSQL_rec *) (estate->datums[recfield->recparentno]);

				/*
				 * Check that there is already a tuple in the record. We need
				 * that because records don't have any predefined field
				 * structure.
				 */
				if (!HeapTupleIsValid(rec->tup))
					ereport(ERROR,
						  (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
						   errmsg("record \"%s\" is not assigned yet",
								  rec->refname),
						   errdetail("The tuple structure of a not-yet-assigned record is indeterminate.")));

				/*
				 * Get the number of the records field to change and the
				 * number of attributes in the tuple.
				 */
				fno = SPI_fnumber(rec->tupdesc, recfield->fieldname);
				if (fno == SPI_ERROR_NOATTRIBUTE)
					ereport(ERROR,
							(errcode(ERRCODE_UNDEFINED_COLUMN),
							 errmsg("record \"%s\" has no field \"%s\"",
									rec->refname, recfield->fieldname)));
				fno--;
				natts = rec->tupdesc->natts;

				/*
				 * Set up values/datums arrays for heap_form_tuple.	For all
				 * the attributes except the one we want to replace, use the
				 * value that's in the old tuple.
				 */
				values = palloc(sizeof(Datum) * natts);
				nulls = palloc(sizeof(bool) * natts);

				for (i = 0; i < natts; i++)
				{
					if (i == fno)
						continue;
					values[i] = SPI_getbinval(rec->tup, rec->tupdesc,
											  i + 1, &attisnull);
					nulls[i] = attisnull;
				}

				/*
				 * Now insert the new value, being careful to cast it to the
				 * right type.
				 */
				atttype = SPI_gettypeid(rec->tupdesc, fno + 1);
				atttypmod = rec->tupdesc->attrs[fno]->atttypmod;
				attisnull = *isNull;
				values[fno] = exec_simple_cast_value(value,
													 valtype,
													 atttype,
													 atttypmod,
													 attisnull);
				nulls[fno] = attisnull;

				/*
				 * Avoid leaking the result of exec_simple_cast_value, if it
				 * performed a conversion to a pass-by-ref type.
				 */
				if (!attisnull && values[fno] != value && !get_typbyval(atttype))
					mustfree = DatumGetPointer(values[fno]);
				else
					mustfree = NULL;

				/*
				 * Now call heap_form_tuple() to create a new tuple that
				 * replaces the old one in the record.
				 */
				newtup = heap_form_tuple(rec->tupdesc, values, nulls);

				if (rec->freetup)
					heap_freetuple(rec->tup);

				rec->tup = newtup;
				rec->freetup = true;

				pfree(values);
				pfree(nulls);
				if (mustfree)
					pfree(mustfree);

				break;
			}

		case PLPGSQL_DTYPE_ARRAYELEM:
			{
				int			nsubscripts;
				int			i;
				PLpgSQL_expr *subscripts[MAXDIM];
				int			subscriptvals[MAXDIM];
				bool		oldarrayisnull;
				Oid			arraytypeid,
							arrayelemtypeid;
				int16		arraytyplen,
							elemtyplen;
				bool		elemtypbyval;
				char		elemtypalign;
				Datum		oldarraydatum,
							coerced_value;
				ArrayType  *oldarrayval;
				ArrayType  *newarrayval;

				/*
				 * Target is an element of an array
				 *
				 * To handle constructs like x[1][2] := something, we have to
				 * be prepared to deal with a chain of arrayelem datums. Chase
				 * back to find the base array datum, and save the subscript
				 * expressions as we go.  (We are scanning right to left here,
				 * but want to evaluate the subscripts left-to-right to
				 * minimize surprises.)
				 */
				nsubscripts = 0;
				do
				{
					PLpgSQL_arrayelem *arrayelem = (PLpgSQL_arrayelem *) target;

					if (nsubscripts >= MAXDIM)
						ereport(ERROR,
								(errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
								 errmsg("number of array dimensions exceeds the maximum allowed, %d",
										MAXDIM)));
					subscripts[nsubscripts++] = arrayelem->subscript;
					target = estate->datums[arrayelem->arrayparentno];
				} while (target->dtype == PLPGSQL_DTYPE_ARRAYELEM);

				/* Fetch current value of array datum */
				exec_eval_datum(estate, target, InvalidOid,
							  &arraytypeid, &oldarraydatum, &oldarrayisnull);

				arrayelemtypeid = get_element_type(arraytypeid);
				if (!OidIsValid(arrayelemtypeid))
					ereport(ERROR,
							(errcode(ERRCODE_DATATYPE_MISMATCH),
							 errmsg("subscripted object is not an array")));

				get_typlenbyvalalign(arrayelemtypeid,
									 &elemtyplen,
									 &elemtypbyval,
									 &elemtypalign);
				arraytyplen = get_typlen(arraytypeid);

				/*
				 * Allow exec_eval_integer to evaluate non-single
				 * Result (simple expression) queries.
				 */
				SPITupleTable * save_tuptable = estate->eval_tuptable;
				estate->eval_tuptable = NULL;

				/*
				 * Evaluate the subscripts, switch into left-to-right order.
				 * Like ExecEvalArrayRef(), complain if any subscript is null.
				 */
				for (i = 0; i < nsubscripts; i++)
				{
					bool		subisnull;

					subscriptvals[i] =
						exec_eval_integer(estate,
										  subscripts[nsubscripts - 1 - i],
										  &subisnull);

					if (estate->eval_tuptable != NULL)
					{
						SPI_freetuptable(estate->eval_tuptable);
						estate->eval_tuptable = NULL;
					}

					if (subisnull)
						ereport(ERROR,
								(errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
								 errmsg("array subscript in assignment must not be NULL")));
				}

				/* Swap to the caller's tuple table. */
				Assert(estate->eval_tuptable == NULL);
				estate->eval_tuptable = save_tuptable;

				/* Coerce source value to match array element type. */
				coerced_value = exec_simple_cast_value(value,
													   valtype,
													   arrayelemtypeid,
													   -1,
													   *isNull);

				/*
				 * If the original array is null, cons up an empty array so
				 * that the assignment can proceed; we'll end with a
				 * one-element array containing just the assigned-to
				 * subscript.  This only works for varlena arrays, though; for
				 * fixed-length array types we skip the assignment.  We can't
				 * support assignment of a null entry into a fixed-length
				 * array, either, so that's a no-op too.  This is all ugly but
				 * corresponds to the current behavior of ExecEvalArrayRef().
				 */
				if (arraytyplen > 0 &&	/* fixed-length array? */
					(oldarrayisnull || *isNull))
					return;

				if (oldarrayisnull)
					oldarrayval = construct_empty_array(arrayelemtypeid);
				else
					oldarrayval = (ArrayType *) DatumGetPointer(oldarraydatum);

				/*
				 * Build the modified array value.
				 */
				newarrayval = array_set(oldarrayval,
										nsubscripts,
										subscriptvals,
										coerced_value,
										*isNull,
										arraytyplen,
										elemtyplen,
										elemtypbyval,
										elemtypalign);

				/*
				 * Avoid leaking the result of exec_simple_cast_value, if it
				 * performed a conversion to a pass-by-ref type.
				 */
				if (!*isNull && coerced_value != value && !elemtypbyval)
					pfree(DatumGetPointer(coerced_value));

				/*
				 * Assign the new array to the base variable.  It's never NULL
				 * at this point.
				 */
				*isNull = false;
				exec_assign_value(estate, target,
								  PointerGetDatum(newarrayval),
								  arraytypeid, isNull);

				/*
				 * Avoid leaking the modified array value, too.
				 */
				pfree(newarrayval);
				break;
			}

		default:
			elog(ERROR, "unrecognized dtype: %d", target->dtype);
	}
}

/*
 * exec_eval_datum				Get current value of a PLpgSQL_datum
 *
 * The type oid, value in Datum format, and null flag are returned.
 *
 * If expectedtypeid isn't InvalidOid, it is checked against the actual type.
 *
 * At present this doesn't handle PLpgSQL_expr or PLpgSQL_arrayelem datums.
 *
 * NOTE: caller must not modify the returned value, since it points right
 * at the stored value in the case of pass-by-reference datatypes.	In some
 * cases we have to palloc a return value, and in such cases we put it into
 * the estate's short-term memory context.
 */
static void
exec_eval_datum(PLpgSQL_execstate *estate,
				PLpgSQL_datum *datum,
				Oid expectedtypeid,
				Oid *typeid,
				Datum *value,
				bool *isnull)
{
	MemoryContext oldcontext;

	switch (datum->dtype)
	{
		case PLPGSQL_DTYPE_VAR:
			{
				PLpgSQL_var *var = (PLpgSQL_var *) datum;

				*typeid = var->datatype->typoid;
				*value = var->value;
				*isnull = var->isnull;
				if (expectedtypeid != InvalidOid && expectedtypeid != *typeid)
					ereport(ERROR,
							(errcode(ERRCODE_DATATYPE_MISMATCH),
							 errmsg("type of \"%s\" does not match that when preparing the plan",
									var->refname)));
				break;
			}

		case PLPGSQL_DTYPE_ROW:
			{
				PLpgSQL_row *row = (PLpgSQL_row *) datum;
				HeapTuple	tup;

				if (!row->rowtupdesc)	/* should not happen */
					elog(ERROR, "row variable has no tupdesc");
				/* Make sure we have a valid type/typmod setting */
				BlessTupleDesc(row->rowtupdesc);
				oldcontext = MemoryContextSwitchTo(estate->eval_econtext->ecxt_per_tuple_memory);
				tup = make_tuple_from_row(estate, row, row->rowtupdesc);
				if (tup == NULL)	/* should not happen */
					elog(ERROR, "row not compatible with its own tupdesc");
				MemoryContextSwitchTo(oldcontext);
				*typeid = row->rowtupdesc->tdtypeid;
				*value = HeapTupleGetDatum(tup);
				*isnull = false;
				if (expectedtypeid != InvalidOid && expectedtypeid != *typeid)
					ereport(ERROR,
							(errcode(ERRCODE_DATATYPE_MISMATCH),
							 errmsg("type of \"%s\" does not match that when preparing the plan",
									row->refname)));
				break;
			}

		case PLPGSQL_DTYPE_REC:
			{
				PLpgSQL_rec *rec = (PLpgSQL_rec *) datum;
				HeapTupleData worktup;

				if (!HeapTupleIsValid(rec->tup))
					ereport(ERROR,
						  (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
						   errmsg("record \"%s\" is not assigned yet",
								  rec->refname),
						   errdetail("The tuple structure of a not-yet-assigned record is indeterminate.")));
				Assert(rec->tupdesc != NULL);
				/* Make sure we have a valid type/typmod setting */
				BlessTupleDesc(rec->tupdesc);

				/*
				 * In a trigger, the NEW and OLD parameters are likely to be
				 * on-disk tuples that don't have the desired Datum fields.
				 * Copy the tuple body and insert the right values.
				 */
				oldcontext = MemoryContextSwitchTo(estate->eval_econtext->ecxt_per_tuple_memory);
				heap_copytuple_with_tuple(rec->tup, &worktup);
				HeapTupleHeaderSetDatumLength(worktup.t_data, worktup.t_len);
				HeapTupleHeaderSetTypeId(worktup.t_data, rec->tupdesc->tdtypeid);
				HeapTupleHeaderSetTypMod(worktup.t_data, rec->tupdesc->tdtypmod);
				MemoryContextSwitchTo(oldcontext);
				*typeid = rec->tupdesc->tdtypeid;
				*value = HeapTupleGetDatum(&worktup);
				*isnull = false;
				if (expectedtypeid != InvalidOid && expectedtypeid != *typeid)
					ereport(ERROR,
							(errcode(ERRCODE_DATATYPE_MISMATCH),
							 errmsg("type of \"%s\" does not match that when preparing the plan",
									rec->refname)));
				break;
			}

		case PLPGSQL_DTYPE_RECFIELD:
			{
				PLpgSQL_recfield *recfield = (PLpgSQL_recfield *) datum;
				PLpgSQL_rec *rec;
				int			fno;

				rec = (PLpgSQL_rec *) (estate->datums[recfield->recparentno]);
				if (!HeapTupleIsValid(rec->tup))
					ereport(ERROR,
						  (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
						   errmsg("record \"%s\" is not assigned yet",
								  rec->refname),
						   errdetail("The tuple structure of a not-yet-assigned record is indeterminate.")));
				fno = SPI_fnumber(rec->tupdesc, recfield->fieldname);
				if (fno == SPI_ERROR_NOATTRIBUTE)
					ereport(ERROR,
							(errcode(ERRCODE_UNDEFINED_COLUMN),
							 errmsg("record \"%s\" has no field \"%s\"",
									rec->refname, recfield->fieldname)));
				*typeid = SPI_gettypeid(rec->tupdesc, fno);
				*value = SPI_getbinval(rec->tup, rec->tupdesc, fno, isnull);
				if (expectedtypeid != InvalidOid && expectedtypeid != *typeid)
					ereport(ERROR,
							(errcode(ERRCODE_DATATYPE_MISMATCH),
							 errmsg("type of \"%s.%s\" does not match that when preparing the plan",
									rec->refname, recfield->fieldname)));
				break;
			}

		case PLPGSQL_DTYPE_TRIGARG:
			{
				PLpgSQL_trigarg *trigarg = (PLpgSQL_trigarg *) datum;
				int			tgargno;

				*typeid = TEXTOID;
				tgargno = exec_eval_integer(estate, trigarg->argnum, isnull);
				if (*isnull || tgargno < 0 || tgargno >= estate->trig_nargs)
				{
					*value = (Datum) 0;
					*isnull = true;
				}
				else
				{
					*value = estate->trig_argv[tgargno];
					*isnull = false;
				}
				if (expectedtypeid != InvalidOid && expectedtypeid != *typeid)
					ereport(ERROR,
							(errcode(ERRCODE_DATATYPE_MISMATCH),
							 errmsg("type of tgargv[%d] does not match that when preparing the plan",
									tgargno)));
				break;
			}

		default:
			elog(ERROR, "unrecognized dtype: %d", datum->dtype);
	}
}

/* ----------
 * exec_eval_integer		Evaluate an expression, coerce result to int4
 *
 * Note we do not do exec_eval_cleanup here; the caller must do it at
 * some later point.  (We do this because the caller may be holding the
 * results of other, pass-by-reference, expression evaluations, such as
 * an array value to be subscripted.  Also see notes in exec_eval_simple_expr
 * about allocation of the parameter array.)
 * ----------
 */
static int
exec_eval_integer(PLpgSQL_execstate *estate,
				  PLpgSQL_expr *expr,
				  bool *isNull)
{
	Datum		exprdatum;
	Oid			exprtypeid;

	exprdatum = exec_eval_expr(estate, expr, isNull, &exprtypeid);
	exprdatum = exec_simple_cast_value(exprdatum, exprtypeid,
									   INT4OID, -1,
									   *isNull);
	return DatumGetInt32(exprdatum);
}

/* ----------
 * exec_eval_boolean		Evaluate an expression, coerce result to bool
 *
 * Note we do not do exec_eval_cleanup here; the caller must do it at
 * some later point.
 * ----------
 */
static bool
exec_eval_boolean(PLpgSQL_execstate *estate,
				  PLpgSQL_expr *expr,
				  bool *isNull)
{
	Datum		exprdatum;
	Oid			exprtypeid;

	exprdatum = exec_eval_expr(estate, expr, isNull, &exprtypeid);
	exprdatum = exec_simple_cast_value(exprdatum, exprtypeid,
									   BOOLOID, -1,
									   *isNull);
	return DatumGetBool(exprdatum);
}

/* ----------
 * exec_eval_expr			Evaluate an expression and return
 *					the result Datum.
 *
 * NOTE: caller must do exec_eval_cleanup when done with the Datum.
 * ----------
 */
static Datum
exec_eval_expr(PLpgSQL_execstate *estate,
			   PLpgSQL_expr *expr,
			   bool *isNull,
			   Oid *rettype)
{
	int			rc;

	/*
	 * If not already done create a plan for this expression
	 */
	if (expr->plan == NULL)
		exec_prepare_plan(estate, expr);

	/*
	 * If this is a simple expression, bypass SPI and use the executor
	 * directly
	 */
	if (expr->expr_simple_expr != NULL)
		return exec_eval_simple_expr(estate, expr, isNull, rettype);

	rc = exec_run_select(estate, expr, 2, NULL);
	if (rc != SPI_OK_SELECT)
		ereport(ERROR,
				(errcode(ERRCODE_WRONG_OBJECT_TYPE),
				 errmsg("query \"%s\" did not return data", expr->query)));

	/*
	 * If there are no rows selected, the result is NULL.
	 */
	if (estate->eval_processed == 0)
	{
		*isNull = true;
		return (Datum) 0;
	}

	/*
	 * Check that the expression returned one single Datum
	 */
	if (estate->eval_processed > 1)
		ereport(ERROR,
				(errcode(ERRCODE_CARDINALITY_VIOLATION),
				 errmsg("query \"%s\" returned more than one row",
						expr->query)));
	if (estate->eval_tuptable->tupdesc->natts != 1)
		ereport(ERROR,
				(errcode(ERRCODE_SYNTAX_ERROR),
				 errmsg("query \"%s\" returned %d columns", expr->query,
						estate->eval_tuptable->tupdesc->natts)));

	/*
	 * Return the result and its type
	 */
	*rettype = SPI_gettypeid(estate->eval_tuptable->tupdesc, 1);
	return SPI_getbinval(estate->eval_tuptable->vals[0],
						 estate->eval_tuptable->tupdesc, 1, isNull);
}


/* ----------
 * exec_run_select			Execute a select query
 * ----------
 */
static int
exec_run_select(PLpgSQL_execstate *estate,
				PLpgSQL_expr *expr, long maxtuples, Portal *portalP)
{
	int			i;
	Datum	   *values;
	char	   *nulls;
	int			rc;

	/* if we find a cached plan, check if we want to use it */
	if (expr->plan != NULL)
	{
		exec_free_plan(expr);
	}

	/*
	 * generate the plan if needed
	 */
	if (expr->plan == NULL)
		exec_prepare_plan(estate, expr);

	/*
	 * Now build up the values and nulls arguments for SPI_execute_plan()
	 */
	values = (Datum *) palloc(expr->nparams * sizeof(Datum));
	nulls = (char *) palloc(expr->nparams * sizeof(char));

	for (i = 0; i < expr->nparams; i++)
	{
		PLpgSQL_datum *datum = estate->datums[expr->params[i]];
		Oid			paramtypeid;
		bool		paramisnull;

		exec_eval_datum(estate, datum, expr->plan_argtypes[i],
						&paramtypeid, &values[i], &paramisnull);
		if (paramisnull)
			nulls[i] = 'n';
		else
			nulls[i] = ' ';
	}

	/*
	 * If a portal was requested, put the query into the portal
	 */
	if (portalP != NULL)
	{
		*portalP = SPI_cursor_open(NULL, expr->plan, values, nulls,
								   estate->readonly_func);
		if (*portalP == NULL)
			elog(ERROR, "could not open implicit cursor for query \"%s\": %s",
				 expr->query, SPI_result_code_string(SPI_result));
		pfree(values);
		pfree(nulls);
		return SPI_OK_CURSOR;
	}

	/*
	 * Execute the query
	 */
	rc = SPI_execute_plan(expr->plan, values, nulls,
						  estate->readonly_func, maxtuples);
	if (rc != SPI_OK_SELECT)
		ereport(ERROR,
				(errcode(ERRCODE_SYNTAX_ERROR),
				 errmsg("query \"%s\" is not a SELECT", expr->query)));

	/* Save query results for eventual cleanup */
	Assert(estate->eval_tuptable == NULL);
	estate->eval_tuptable = SPI_tuptable;
	estate->eval_processed = SPI_processed;
	estate->eval_lastoid = SPI_lastoid;

	pfree(values);
	pfree(nulls);

	return rc;
}


/* ----------
 * exec_eval_simple_expr -		Evaluate a simple expression returning
 *								a Datum by directly calling ExecEvalExpr().
 *
 * Note: if pass-by-reference, the result is in the eval_econtext's
 * temporary memory context.  It will be freed when exec_eval_cleanup
 * is done.
 * ----------
 */
static Datum
exec_eval_simple_expr(PLpgSQL_execstate *estate,
					  PLpgSQL_expr *expr,
					  bool *isNull,
					  Oid *rettype)
{
	Datum		retval;
	ExprContext *econtext = estate->eval_econtext;
	ParamListInfo paramLI;
	int			i;
	Snapshot	saveActiveSnapshot;

	/*
	 * Pass back previously-determined result type.
	 */
	*rettype = expr->expr_simple_type;

	/*
	 * Prepare the expression for execution, if it's not been done already in
	 * the current eval_estate.
	 */
	if (expr->expr_simple_id != estate->eval_estate_simple_id)
	{
		expr->expr_simple_state = ExecPrepareExpr(expr->expr_simple_expr,
												  estate->eval_estate);
		expr->expr_simple_id = estate->eval_estate_simple_id;
	}

	/*
	 * Param list can live in econtext's temporary memory context.
	 *
	 * XXX think about avoiding repeated palloc's for param lists? Beware
	 * however that this routine is re-entrant: exec_eval_datum() can call it
	 * back for subscript evaluation, and so there can be a need to have more
	 * than one active param list.
	 */
	if (expr->nparams > 0)
	{
		/* sizeof(ParamListInfoData) includes the first array element */
		paramLI = (ParamListInfo)
			MemoryContextAlloc(econtext->ecxt_per_tuple_memory,
							   sizeof(ParamListInfoData) +
							   (expr->nparams - 1) *sizeof(ParamExternData));
		paramLI->numParams = expr->nparams;

		for (i = 0; i < expr->nparams; i++)
		{
			ParamExternData *prm = &paramLI->params[i];
			PLpgSQL_datum *datum = estate->datums[expr->params[i]];

			prm->pflags = 0;
			exec_eval_datum(estate, datum, expr->plan_argtypes[i],
							&prm->ptype,
							&prm->value, &prm->isnull);
		}
	}
	else
		paramLI = NULL;

	/*
	 * Now we can safely make the econtext point to the param list.
	 */
	econtext->ecxt_param_list_info = paramLI;

	/*
	 * We have to do some of the things SPI_execute_plan would do, in
	 * particular advance the snapshot if we are in a non-read-only function.
	 * Without this, stable functions within the expression would fail to see
	 * updates made so far by our own function.
	 */
	SPI_push();
	saveActiveSnapshot = ActiveSnapshot;

	PG_TRY();
	{
		MemoryContext oldcontext;

		oldcontext = MemoryContextSwitchTo(econtext->ecxt_per_tuple_memory);
		if (!estate->readonly_func)
		{
			CommandCounterIncrement();
			ActiveSnapshot = CopySnapshot(GetTransactionSnapshot());
		}

		/*
		 * Finally we can call the executor to evaluate the expression
		 */
		retval = ExecEvalExpr(expr->expr_simple_state,
							  econtext,
							  isNull,
							  NULL);
		MemoryContextSwitchTo(oldcontext);
	}
	PG_CATCH();
	{
		/* Restore global vars and propagate error */
		ActiveSnapshot = saveActiveSnapshot;
		PG_RE_THROW();
	}
	PG_END_TRY();

	ActiveSnapshot = saveActiveSnapshot;
	SPI_pop();

	/*
	 * That's it.
	 */
	return retval;
}


/* ----------
 * exec_move_row			Move one tuple's values into a record or row
 * ----------
 */
static void
exec_move_row(PLpgSQL_execstate *estate,
			  PLpgSQL_rec *rec,
			  PLpgSQL_row *row,
			  HeapTuple tup, TupleDesc tupdesc)
{
	/*
	 * Record is simple - just copy the tuple and its descriptor into the
	 * record variable
	 */
	if (rec != NULL)
	{
		/*
		 * Copy input first, just in case it is pointing at variable's value
		 */
		if (HeapTupleIsValid(tup))
			tup = heap_copytuple(tup);
		else if (tupdesc)
		{
			/* If we have a tupdesc but no data, form an all-nulls tuple */
			bool   *nulls;

			nulls = (bool *) palloc(tupdesc->natts * sizeof(bool));
			memset(nulls, true, tupdesc->natts * sizeof(bool));

			tup = heap_form_tuple(tupdesc, NULL, nulls);

			pfree(nulls);
		}

		if (tupdesc)
			tupdesc = CreateTupleDescCopy(tupdesc);

		/* Free the old value ... */
		if (rec->freetup)
		{
			heap_freetuple(rec->tup);
			rec->freetup = false;
		}
		if (rec->freetupdesc)
		{
			FreeTupleDesc(rec->tupdesc);
			rec->freetupdesc = false;
		}

		/* ... and install the new */
		if (HeapTupleIsValid(tup))
		{
			rec->tup = tup;
			rec->freetup = true;
		}
		else
			rec->tup = NULL;

		if (tupdesc)
		{
			rec->tupdesc = tupdesc;
			rec->freetupdesc = true;
		}
		else
			rec->tupdesc = NULL;

		return;
	}

	/*
	 * Row is a bit more complicated in that we assign the individual
	 * attributes of the tuple to the variables the row points to.
	 *
	 * NOTE: this code used to demand row->nfields == HeapTupleHeaderGetNatts(tup->t_data,
	 * but that's wrong.  The tuple might have more fields than we expected if
	 * it's from an inheritance-child table of the current table, or it might
	 * have fewer if the table has had columns added by ALTER TABLE. Ignore
	 * extra columns and assume NULL for missing columns, the same as
	 * heap_getattr would do.  We also have to skip over dropped columns in
	 * either the source or destination.
	 *
	 * If we have no tuple data at all, we'll assign NULL to all columns of
	 * the row variable.
	 */
	if (row != NULL)
	{
		int			td_natts = tupdesc ? tupdesc->natts : 0;
		int			t_natts;
		int			fnum;
		int			anum;

		if (HeapTupleIsValid(tup))
			t_natts = HeapTupleHeaderGetNatts(tup->t_data);
		else
			t_natts = 0;

		anum = 0;
		for (fnum = 0; fnum < row->nfields; fnum++)
		{
			PLpgSQL_var *var;
			Datum		value;
			bool		isnull;
			Oid			valtype;

			if (row->varnos[fnum] < 0)
				continue;		/* skip dropped column in row struct */

			var = (PLpgSQL_var *) (estate->datums[row->varnos[fnum]]);

			while (anum < td_natts && tupdesc->attrs[anum]->attisdropped)
				anum++;			/* skip dropped column in tuple */

			if (anum < td_natts)
			{
				if (anum < t_natts)
					value = SPI_getbinval(tup, tupdesc, anum + 1, &isnull);
				else
				{
					value = (Datum) 0;
					isnull = true;
				}
				valtype = SPI_gettypeid(tupdesc, anum + 1);
				anum++;
			}
			else
			{
				value = (Datum) 0;
				isnull = true;
				valtype = InvalidOid;
			}

			exec_assign_value(estate, (PLpgSQL_datum *) var,
							  value, valtype, &isnull);
		}

		return;
	}

	elog(ERROR, "unsupported target");
}

/* ----------
 * make_tuple_from_row		Make a tuple from the values of a row object
 *
 * A NULL return indicates rowtype mismatch; caller must raise suitable error
 * ----------
 */
static HeapTuple
make_tuple_from_row(PLpgSQL_execstate *estate,
					PLpgSQL_row *row,
					TupleDesc tupdesc)
{
	int			natts = tupdesc->natts;
	HeapTuple	tuple;
	Datum	   *dvalues;
	bool	   *nulls;
	int			i;

	if (natts != row->nfields)
		return NULL;

	dvalues = (Datum *) palloc0(natts * sizeof(Datum));
	nulls = (bool *) palloc(natts * sizeof(bool));

	for (i = 0; i < natts; i++)
	{
		Oid			fieldtypeid;

		if (tupdesc->attrs[i]->attisdropped)
		{
			nulls[i] = true;	/* leave the column as null */
			continue;
		}
		if (row->varnos[i] < 0) /* should not happen */
			elog(ERROR, "dropped rowtype entry for non-dropped column");

		exec_eval_datum(estate, estate->datums[row->varnos[i]],
						InvalidOid, &fieldtypeid, &dvalues[i], &nulls[i]);
		if (fieldtypeid != tupdesc->attrs[i]->atttypid)
			return NULL;
	}

	tuple = heap_form_tuple(tupdesc, dvalues, nulls);

	pfree(dvalues);
	pfree(nulls);

	return tuple;
}

/* ----------
 * convert_value_to_string			Convert a non-null Datum to C string
 *
 * Note: callers generally assume that the result is a palloc'd string and
 * should be pfree'd.  This is not all that safe an assumption ...
 *
 * Note: not caching the conversion function lookup is bad for performance.
 * ----------
 */
static char *
convert_value_to_string(Datum value, Oid valtype)
{
	char	   *str;
	Oid			typoutput;
	bool		typIsVarlena;

	getTypeOutputInfo(valtype, &typoutput, &typIsVarlena);

	/*
	 * We do SPI_push to allow the datatype output function to use SPI.
	 * However we do not mess around with CommandCounterIncrement or advancing
	 * the snapshot, which means that a stable output function would not see
	 * updates made so far by our own function.  The use-case for such
	 * scenarios seems too narrow to justify the cycles that would be
	 * expended.
	 */
	SPI_push();

	str = OidOutputFunctionCall(typoutput, value);

	SPI_pop();

	return str;
}

/* ----------
 * exec_cast_value			Cast a value if required
 * ----------
 */
static Datum
exec_cast_value(Datum value, Oid valtype,
				Oid reqtype,
				FmgrInfo *reqinput,
				Oid reqtypioparam,
				int32 reqtypmod,
				bool isnull)
{
	/*
	 * If the type of the queries return value isn't that of the variable,
	 * convert it.
	 */
	if (valtype != reqtype || reqtypmod != -1)
	{
		if (!isnull)
		{
			char	   *extval;

			extval = convert_value_to_string(value, valtype);

			/* Allow input function to use SPI ... see notes above */
			SPI_push();

			value = InputFunctionCall(reqinput, extval,
									  reqtypioparam, reqtypmod);

			SPI_pop();

			pfree(extval);
		}
		else
		{
			SPI_push();

			value = InputFunctionCall(reqinput, NULL,
									  reqtypioparam, reqtypmod);

			SPI_pop();
		}
	}

	return value;
}

/* ----------
 * exec_simple_cast_value			Cast a value if required
 *
 * As above, but need not supply details about target type.  Note that this
 * is slower than exec_cast_value with cached type info, and so should be
 * avoided in heavily used code paths.
 * ----------
 */
static Datum
exec_simple_cast_value(Datum value, Oid valtype,
					   Oid reqtype, int32 reqtypmod,
					   bool isnull)
{
	if (!isnull)
	{
		if (valtype != reqtype || reqtypmod != -1)
		{
			Oid			typinput;
			Oid			typioparam;
			FmgrInfo	finfo_input;

			getTypeInputInfo(reqtype, &typinput, &typioparam);

			fmgr_info(typinput, &finfo_input);

			value = exec_cast_value(value,
									valtype,
									reqtype,
									&finfo_input,
									typioparam,
									reqtypmod,
									isnull);
		}
	}

	return value;
}


/* ----------
 * exec_simple_check_node -		Recursively check if an expression
 *								is made only of simple things we can
 *								hand out directly to ExecEvalExpr()
 *								instead of calling SPI.
 * ----------
 */
static bool
exec_simple_check_node(Node *node)
{
	if (node == NULL)
		return TRUE;

	switch (nodeTag(node))
	{
		case T_Const:
			return TRUE;

		case T_Param:
			return TRUE;

		case T_ArrayRef:
			{
				ArrayRef   *expr = (ArrayRef *) node;

				if (!exec_simple_check_node((Node *) expr->refupperindexpr))
					return FALSE;
				if (!exec_simple_check_node((Node *) expr->reflowerindexpr))
					return FALSE;
				if (!exec_simple_check_node((Node *) expr->refexpr))
					return FALSE;
				if (!exec_simple_check_node((Node *) expr->refassgnexpr))
					return FALSE;

				return TRUE;
			}

		case T_FuncExpr:
			{
				FuncExpr   *expr = (FuncExpr *) node;

				if (expr->funcretset)
					return FALSE;
				if (!exec_simple_check_node((Node *) expr->args))
					return FALSE;

				return TRUE;
			}

		case T_OpExpr:
			{
				OpExpr	   *expr = (OpExpr *) node;

				if (expr->opretset)
					return FALSE;
				if (!exec_simple_check_node((Node *) expr->args))
					return FALSE;

				return TRUE;
			}

		case T_DistinctExpr:
			{
				DistinctExpr *expr = (DistinctExpr *) node;

				if (expr->opretset)
					return FALSE;
				if (!exec_simple_check_node((Node *) expr->args))
					return FALSE;

				return TRUE;
			}

		case T_ScalarArrayOpExpr:
			{
				ScalarArrayOpExpr *expr = (ScalarArrayOpExpr *) node;

				if (!exec_simple_check_node((Node *) expr->args))
					return FALSE;

				return TRUE;
			}

		case T_BoolExpr:
			{
				BoolExpr   *expr = (BoolExpr *) node;

				if (!exec_simple_check_node((Node *) expr->args))
					return FALSE;

				return TRUE;
			}

		case T_FieldSelect:
			return exec_simple_check_node((Node *) ((FieldSelect *) node)->arg);

		case T_FieldStore:
			{
				FieldStore *expr = (FieldStore *) node;

				if (!exec_simple_check_node((Node *) expr->arg))
					return FALSE;
				if (!exec_simple_check_node((Node *) expr->newvals))
					return FALSE;

				return TRUE;
			}

		case T_RelabelType:
			return exec_simple_check_node((Node *) ((RelabelType *) node)->arg);

		case T_ConvertRowtypeExpr:
			return exec_simple_check_node((Node *) ((ConvertRowtypeExpr *) node)->arg);

		case T_CaseExpr:
			{
				CaseExpr   *expr = (CaseExpr *) node;

				if (!exec_simple_check_node((Node *) expr->arg))
					return FALSE;
				if (!exec_simple_check_node((Node *) expr->args))
					return FALSE;
				if (!exec_simple_check_node((Node *) expr->defresult))
					return FALSE;

				return TRUE;
			}

		case T_CaseWhen:
			{
				CaseWhen   *when = (CaseWhen *) node;

				if (!exec_simple_check_node((Node *) when->expr))
					return FALSE;
				if (!exec_simple_check_node((Node *) when->result))
					return FALSE;

				return TRUE;
			}

		case T_CaseTestExpr:
			return TRUE;

		case T_ArrayExpr:
			{
				ArrayExpr  *expr = (ArrayExpr *) node;

				if (!exec_simple_check_node((Node *) expr->elements))
					return FALSE;

				return TRUE;
			}

		case T_RowExpr:
			{
				RowExpr    *expr = (RowExpr *) node;

				if (!exec_simple_check_node((Node *) expr->args))
					return FALSE;

				return TRUE;
			}

		case T_RowCompareExpr:
			{
				RowCompareExpr *expr = (RowCompareExpr *) node;

				if (!exec_simple_check_node((Node *) expr->largs))
					return FALSE;
				if (!exec_simple_check_node((Node *) expr->rargs))
					return FALSE;

				return TRUE;
			}

		case T_CoalesceExpr:
			{
				CoalesceExpr *expr = (CoalesceExpr *) node;

				if (!exec_simple_check_node((Node *) expr->args))
					return FALSE;

				return TRUE;
			}

		case T_MinMaxExpr:
			{
				MinMaxExpr *expr = (MinMaxExpr *) node;

				if (!exec_simple_check_node((Node *) expr->args))
					return FALSE;

				return TRUE;
			}

		case T_NullIfExpr:
			{
				NullIfExpr *expr = (NullIfExpr *) node;

				if (expr->opretset)
					return FALSE;
				if (!exec_simple_check_node((Node *) expr->args))
					return FALSE;

				return TRUE;
			}

		case T_NullTest:
			return exec_simple_check_node((Node *) ((NullTest *) node)->arg);

		case T_BooleanTest:
			return exec_simple_check_node((Node *) ((BooleanTest *) node)->arg);

		case T_CoerceToDomain:
			return exec_simple_check_node((Node *) ((CoerceToDomain *) node)->arg);

		case T_CoerceToDomainValue:
			return TRUE;

		case T_List:
			{
				List	   *expr = (List *) node;
				ListCell   *l;

				foreach(l, expr)
				{
					if (!exec_simple_check_node(lfirst(l)))
						return FALSE;
				}

				return TRUE;
			}

		default:
			return FALSE;
	}
}


/* ----------
 * exec_simple_check_plan -		Check if a plan is simple enough to
 *								be evaluated by ExecEvalExpr() instead
 *								of SPI.
 * ----------
 */
static void
exec_simple_check_plan(PLpgSQL_expr *expr)
{
	_SPI_plan  *spi_plan = (_SPI_plan *) expr->plan;
	PlannedStmt *stmt;
	Plan	   *plan;
	TargetEntry *tle;

	expr->expr_simple_expr = NULL;

	/*
	 * 1. We can only evaluate queries that resulted in one single execution
	 * plan
	 */
	if (list_length(spi_plan->ptlist) != 1)
		return;

	/*
	 * MPP-8038: Utility statements get here too, so make sure this is
	 * planned
	 */
	if (IsA(linitial(spi_plan->ptlist), PlannedStmt))
	{
		stmt = (PlannedStmt *) linitial(spi_plan->ptlist);
		plan = stmt ? stmt->planTree : NULL;
	}
	else
	{
		/* This is a utility statement */
		plan = NULL;
	}

	/*
	 * 2. It must be a RESULT plan --> no scan's required
	 */
	if (plan == NULL)			/* utility statement produces this */
		return;

	if (!IsA(plan, Result))
		return;

	/*
	 * 3. Can't have any subplan or qual clause, either
	 */
	if (plan->lefttree != NULL ||
		plan->righttree != NULL ||
		plan->initPlan != NULL ||
		plan->qual != NULL ||
		((Result *) plan)->resconstantqual != NULL)
		return;

	/*
	 * 4. The plan must have a single attribute as result
	 */
	if (list_length(plan->targetlist) != 1)
		return;

	tle = (TargetEntry *) linitial(plan->targetlist);

	/*
	 * 5. Check that all the nodes in the expression are non-scary.
	 */
	if (!exec_simple_check_node((Node *) tle->expr))
		return;

	/*
	 * Yes - this is a simple expression.  Mark it as such, and initialize
	 * state to "not valid in current transaction".
	 */
	expr->expr_simple_expr = tle->expr;
	expr->expr_simple_state = NULL;
	expr->expr_simple_id = -1;
	/* Also stash away the expression result type */
	expr->expr_simple_type = exprType((Node *) tle->expr);
}

/*
 * Check two tupledescs have matching number and types of attributes
 */
static bool
compatible_tupdesc(TupleDesc td1, TupleDesc td2)
{
	int			i;

	if (td1->natts != td2->natts)
		return false;

	for (i = 0; i < td1->natts; i++)
	{
		if (td1->attrs[i]->atttypid != td2->attrs[i]->atttypid)
			return false;
	}

	return true;
}

/* ----------
 * exec_set_found			Set the global found variable
 *					to true/false
 * ----------
 */
static void
exec_set_found(PLpgSQL_execstate *estate, bool state)
{
	PLpgSQL_var *var;

	var = (PLpgSQL_var *) (estate->datums[estate->found_varno]);
	var->value = (Datum) state;
	var->isnull = false;
}

/*
 * plpgsql_create_econtext --- create an eval_econtext for the current function
 *
 * We may need to create a new eval_estate too, if there's not one already
 * for the current (sub) transaction.  The EState will be cleaned up at
 * (sub) transaction end.
 */
static void
plpgsql_create_econtext(PLpgSQL_execstate *estate)
{
	SubTransactionId my_subxid = GetCurrentSubTransactionId();
	SimpleEstateStackEntry *entry = simple_estate_stack;

	/* Create new EState if not one for current subxact */
	if (entry == NULL ||
		entry->xact_subxid != my_subxid)
	{
		MemoryContext oldcontext;

		/* Stack entries are kept in TopTransactionContext for simplicity */
		entry = (SimpleEstateStackEntry *)
			MemoryContextAlloc(TopTransactionContext,
							   sizeof(SimpleEstateStackEntry));

		/* But each EState should be a child of its CurTransactionContext */
		oldcontext = MemoryContextSwitchTo(CurTransactionContext);
		entry->xact_eval_estate = CreateExecutorState();
		MemoryContextSwitchTo(oldcontext);

		/* Assign a reasonably-unique ID to this EState */
		entry->xact_estate_simple_id = simple_estate_id_counter++;
		entry->xact_subxid = my_subxid;

		entry->next = simple_estate_stack;
		simple_estate_stack = entry;
	}

	/* Link plpgsql estate to it */
	estate->eval_estate = entry->xact_eval_estate;
	estate->eval_estate_simple_id = entry->xact_estate_simple_id;

	/* And create a child econtext for the current function */
	estate->eval_econtext = CreateExprContext(estate->eval_estate);
}

/*
 * plpgsql_xact_cb --- post-transaction-commit-or-abort cleanup
 *
 * If a simple-expression EState was created in the current transaction,
 * it has to be cleaned up.
 */
void
plpgsql_xact_cb(XactEvent event, void *arg)
{
	/*
	 * If we are doing a clean transaction shutdown, free the EState (so that
	 * any remaining resources will be released correctly). In an abort, we
	 * expect the regular abort recovery procedures to release everything of
	 * interest.  We don't need to free the individual stack entries since
	 * TopTransactionContext is about to go away anyway.
	 *
	 * Note: if plpgsql_subxact_cb is doing its job, there should be at most
	 * one stack entry, but we may as well code this as a loop.
	 */
	if (event != XACT_EVENT_ABORT)
	{
		while (simple_estate_stack != NULL)
		{
			FreeExecutorState(simple_estate_stack->xact_eval_estate);
			simple_estate_stack = simple_estate_stack->next;
		}
	}
	else
		simple_estate_stack = NULL;
}

/*
 * plpgsql_subxact_cb --- post-subtransaction-commit-or-abort cleanup
 *
 * Make sure any simple-expression econtexts created in the current
 * subtransaction get cleaned up.  We have to do this explicitly because
 * no other code knows which child econtexts of simple_eval_estate belong
 * to which level of subxact.
 */
void
plpgsql_subxact_cb(SubXactEvent event, SubTransactionId mySubid,
				   SubTransactionId parentSubid, void *arg)
{
	if (event == SUBXACT_EVENT_START_SUB)
		return;

	if (simple_estate_stack != NULL &&
		simple_estate_stack->xact_subxid == mySubid)
	{
		SimpleEstateStackEntry *next;
		
		if (event == SUBXACT_EVENT_COMMIT_SUB)
			FreeExecutorState(simple_estate_stack->xact_eval_estate);
		next = simple_estate_stack->next;
		pfree(simple_estate_stack);
		simple_estate_stack = next;
	}
}

/*
 * free_var --- pfree any pass-by-reference value of the variable.
 *
 * This should always be followed by some assignment to var->value,
 * as it leaves a dangling pointer.
 */
static void
free_var(PLpgSQL_var *var)
{
	if (var->freeval)
	{
		pfree(DatumGetPointer(var->value));
		var->freeval = false;
	}
}



/* ----------
 * exec_check_cache_plan -		Check if a plan can be cached
 * 
 * This routine checks if plan can be cached to avoid stale 
 * plan issues as seen with MPP-16204.
 *
 * 	- If the input expr contains only UTILITY statements, the routine 
 *	  sets cachable to true.
 * ----------
 */
static void
exec_check_cache_plan(PLpgSQL_expr *expr)
{
	_SPI_plan	*spi_plan = (_SPI_plan *) expr->plan; 
	PlannedStmt	*stmt = NULL; 
	Plan		*plan = NULL; 
	ListCell	*plan_list_item = NULL;

	/* 
	 * store the current transaction id. we will only free the plan
	 * if the next invocation of the plan is from a different	
	 * transaction 
	 */
	expr->transaction_id = GetTopTransactionId();

	/* 
	 * we can have multiple PlannedStmt. Walk all of them
	 */
	foreach (plan_list_item, spi_plan->ptlist)
	{
		if (IsA((lfirst(plan_list_item)), PlannedStmt))
		{
			stmt = (PlannedStmt *)lfirst(plan_list_item);
			plan = stmt ? stmt->planTree : NULL;
		}
		else
		{
			/* UTILITY statements */
		  	plan = NULL;
		}

		if (plan == NULL)
		{
			continue;	
		}
		else
		{
			expr->cachable = false;
			return;
		}
	}

 	expr->cachable = true;
	return; 
}

/* 
 * exec_free_plan
 * 
 * This routine frees the plan cached by PL/pgSQL under the following 
 * conditions 
 *	- the use_count is 0 . This is to protect the plan under recursive 
 *	  invocations and
 *	- exec_check_cache_plan has indicated that it is not safe to cache the 
 * 	  plan and
 *	- we are not in EXECUTE mode
 * 	- if the plan was compiled in a different transaction (this check is 
 *	  made so we don't free the plans too aggresively.
*/
static void
exec_free_plan(PLpgSQL_expr *expr)
{
	TransactionId txid = GetTopTransactionId();

	if (((_SPI_plan *)expr->plan)->use_count == 0 
		&& !expr->cachable 
		&& Gp_role != GP_ROLE_EXECUTE 
		&& (gp_plpgsql_clear_cache_always || expr->transaction_id != txid)) 
	{
		SPI_freeplan(expr->plan);
		expr->plan = NULL;
	}
}

